Cathy, thanks for all the info. DS has now done a third of EPGY 3 and it turns out that it's primarily a review of the CTY Elementary Problem Solving I course. CTY had recommended starting with that one as an introduction and said it covered the first and second grade curricula. The weird thing is that it also covered long division, without much of an explanation. At least I know not to arbitrarily hold him back from the 4 course.
As for math competitions, he's good at math, but I never considered him a math whiz. But I like the idea of having him do problems he has to think about. I've read about math kangaroo on this board, although there are no locations nearby. It might be a good idea to try some of the problems from past tests as practice.
