I've done SCLG1001 and will be doing SCLG1002, so if my opinion counts...
Readings? Tons. Well, that's partly because I'm a lazy slob, but both SCLG units mentioned state there are approx. 80 pp. of reading per week, although I've often found it to be more. You don't necessarily have to do the required reading in order to bullshit in tutorials, but you might be stuffed when it comes to assessment time (like myself and my pitiful essay). As for difficulty, the lectures can be a bit dry, and tute experience may vary, but the content itself is pretty interesting. It has some difficult concepts, but IMHO it's nothing as long as you do the majority of the readings. And have good writing skills.