This pretty much, it's an individual thing. For the average Joe, 3U is difficult and challenging, but with effort they should be able to do fairly well (80+). I was doing pretty well in 3U, although for me the effort I was putting in wasnt proportional to my results and I believed that my time was better invested elsewhere.Whether one find MX1 hard or not depends on one. Those who are good at maths find it easy. Those who find 2U Advanced manageable, but not too easy, will find MX1 hard just as those who can only manage Maths General 2 may find 2U advanced challenging. So it all depends.