Seeing as your profile indicates that your HSC year, I'm going to try to base my arguments from my experiences in Year 7 and * at SBHS.
Some of my ex-classmates who ended up going to Sydney Boys are suffering badly not only in terms of academics but also in their physical/emotional/mental wellbeing: a lot of them have to wake up super early every Saturday to attend compulsory extra-school sport sessions (they're required to spend 2-3 hours doing sport each weekend under supervision of school teachers at certain venues) and from I've heard, that is also super expensive. That gives them less time for studying/learning academic content. To put that in context: we were all roughly equal in academic performance in primary school, but now in Year 8, most of them are getting B's and C's for the same subjects that I almost always get A's for (they're scoring in the high 70's and low 80's for their core subjects—English, mathematics and science—but I'm getting mostly high 90's). If you're wondering: this isn't specific to just me and them; this is a general trend between students attending Ruse and Sydney Boys High. Some cynics would suggest this could just be the result of the teachers at Ruse marking their students better, but I hardly think so (HSC results prove that JRAHS is obviously waaaaaay ahead of SBHS).
2-3 hours of Saturday sport is not going to take a toll on your personal wellbeing or academics in any way. I'll be surprised if someone actually said that they dedicated that time to their studies. Maybe your friends are unwillingly participating, which may be due to them feeling obliged to take part in competitive Saturday sport. There are however alternatives which only require a 2 hour session during school sport, which I'm pretty sure every school has an allocated time slot for in the week. However I do encourage the participation in these sports, as we do have a pretty good sporting program that caters for even those who have a hard time kicking a soccer ball properly.
As for academic performance, high 70s and low 80s are even bad. If I was in their position I wouldn't need to worry about anything. As for the HSC, the overall performance of a school does not necessarily indicate the performance of an individual. I don't know about Ruse, but the ATARs of SBHS students each year range from 99.95 to the high 70s. HSC rankings are only based off the performance of a cohort of that particular year, and is subject to change from year to year just like the sudden drop of SGHS in 2016. I do have to agree that Ruse does perform a lot better than SBHS each year though.
There's a lot of peer competition at Ruse (mostly between the Korean students, I'll venture to say, and not the Chinese as per conventional wisdom) so the pressure to do well is much higher at Ruse. I often hear students going 'So-and-so top student only got 39/40 for the maths test and I got 40, ahahahah!' and of course this might seem shameful/insulting to that top student, but it's naturally part of life at Ruse. They'll go on to study harder, do better, …, and that's how it works here. On the other hand, SBHS now allows students who did not sit the Selective Test or did not successfully pass the test to gain admission to SBHS to enter if they live close enough. So your son's class at SBHS might be made up of 70% academically gifted students and 30% not-so-gifted students ;p. He might get the impression that he's doing really well in comparison to his close friends/peers, when he's not doing well at all in fact.
Entrance in Year 7 to any Selective Schools is based purely on the Selective test, but we all accept enrollments in other years, mainly in Year 9 and Year 11. The proximity of your residence to the school doesn't really affect the selection process. There have been cases of people living down the road or even as far Campbelltown being accepted into the school. Selection is usually based on the achievements of a student, mainly due to their sporting or musical achievements. But all applicants have to demonstrate academic capability in order to be accepted.
As for one's performance in comparison to their classmates, there's always going to be winners and losers matter what school you go to. Your ranking doesn't determine how capable you are.
I should probably also mention that getting enough sleep is very important for high school students, and saving 30 minutes a day in travel is usually a make-or-break factor in academic performance for younger high school students. At least at Ruse, the students who spend 2-4 hours a day on travel (not joking) are miles behind those who spend <1 hour in academic performance because they're drained of energy, enthusiasm to study when they get home, etc. except for the ones who go to tutoring endlessly. Most of these students also don't get time to finish assignments. One of my classmates at Ruse started his half-yearly assignment on the train and finished when he got to school. (You can probably imagine how well that turned out.)
Sleep is indeed important and does play a factor in academics, but travel isn't a reason for the lack of enthusiasm or energy from students, but rather from poor time management or work ethics. There is always time to study, no matter where you live. The biggest hindrance to the completing of assignments and homework or the preparation for exams is procrastination, or simply not taking schoolwork seriously, which happens a lot, probably in the case of your friend who finished assignment during his commute. There is a mentality among a lot of students that if a certain piece of work doesn't count towards your report then it's not worth doing, which contributes to a student's lack of preparation for an exam, because they waste time gathering notes for something that they would've had if they had just done the work back they were supposed to.
I'm not sure your son would actually enjoy going to an 'all-rounded' school, and if he does, make sure to buy life insurance for him. I'm not even joking when I say that the physical sport training regime at Sydney Boys is ridiculously tough and would probably take a toll on your son's wellbeing. Sport is the almighty god of SBHS.
Do you actually have a grudge against sport or something? Sport might be tough if you choose to do it at a high level in your senior years or you are just unlucky to have a sadistic coach. Otherwise, for juniors its mostly due to their bodies being in their development phases or them simply being unfit. Still, "ridiculously tough" is too much of an exaggeration.
Although, even at James Ruse, sport is by far the most time-consuming subject (9-10 periods for sport, only 8-9 for maths and English per fortnight), it has much less of a priority and one can easily score an A by just doing well in PE theory (i.e. stuff like drug education, nutrition, etc.) and utterly failing actual physical sport. Theory accounts for about 90% of the final report mark in sport, so one could literally get zero in the physical component and still get an A if they tried hard enough in theory + assignments (about 80~85-ish is the cut-off mark for an A). At SBHS, sport is taken very seriously, and it's much easier to get a fail and letters sent home.
I'm not even sure what your sources are right now. The only way you get letters sent home regarding academics is if you don't do your work. Bad grades doesn't warrant it here. PE theory only constitutes the PDH in PDHPE (Personal Development, Health and Physical Education). It doesn't really back up your sport argument. Your emphasis on grades misses the purpose of sport: to exercise and look after your body.
Extra-curricular activities aren't so much of a priority at Ruse either, but students are expected to have a very decent grasp of musical concepts and should be able to play one instrument (already when they start Year 7, not learn as they go through to Year 8) but music as a compulsory subject is dropped in Year 8. Agriculture and agriculture-related activities are prominent at Ruse. Agriculture as a subject is compulsory until and all through Year 10, and it's by far the hardest subject (for me and many other students). It's quite common for Ruse students to get a mark in agriculture of about 10-20 points below their other subjects, and agriculture is the most commonly failed subject here (a surprising number of students get less than 50% for their agriculture half-yearlies and yearlies, which means a retest). But unless you prefer getting your bones broken playing rugby to memorising the names of common sheep breeds, James Ruse is obviously the superior school. Full stop.
If you're trying to promote Ruse here, I really don't think this is doing it... The purpose of schools are not only to educate children on academics, but to also provide them with opportunities to develop and express themselves through co-curricular activities such as sport, music, drama, debating and public speaking. Although it is important for many of us who wish to go to uni to achieve high marks in tests in this flawed education system, we should realise that school is much more than just that. High school is 6 years, and a huge chunk of our lifetime as of now, so live a little. In uni and afterwards, when we talk about high school and our childhoods, we would like to talk about the times we won or lost a game of sport, the times when we got lost on our way to sport, when the team collectively roasted our coach (this happens quite a lot at SBHS), the feeling we get when we play a solo at a jazz concert, the time when we absolutely shut down the other team's arguments in debating or a drama production that you've been part of. You might not have been a star or MVP, but you would have definitely been part of the experience.
I am in no way saying that James Ruse is a bad school. I've some of your prefect videos and Youtube and they have drawn out some good qualities of the school. My biggest problem with your response to the OP was the sole emphasis on academics and marks. We might care about it now, but in the years to come, nobody would even care about what marks they got for their maths test or what ATAR they get.
Hopefully it's not to late yet, but my advice to the OP is that you should ask your son what school he's more interested in. Both schools are great academically so it shouldn't be much of a problem here, but what sort of lifestyle he wants. If he's entering in Year 11 and wants to focus on academics more, maybe Ruse is a better option. I think they outperform the 2nd ranked school each year by a pretty big margin in the HSC, so the standards set in school might be a lot higher although I can't speak for them seeing as I'm not one of their students. If your son is entering in Year 9, SBHS might be a good option since the HSC isn't coming up for a while, meaning that he wouldn't have to worry about academics too much and can devote some more time on co-curricular activities. It is also good to see how he can cope with school work, as the final years of school can be extremely stressful for students and mental health issues are a rising issue. I know how i talked about how sports doesn't really take a toll, but ultimately it really depends on the pressure one puts on themselves to succeed. I have had times when I didn't enjoy playing sport due to being isolated from my friends and played in a more competitive team and ended up feeling left out due to the difference in skill level between me and my teammates. In the end I only played in the lower teams with my friends and found it to be much more enjoyable. If your son can get into the right mindset going into either Ruse or SBHS, then he should have a good time at either school.