A lot of the time, when people discuss EM, they are comparing apples and oranges. I have 2 teacher friends whose districts use Em and they implement it quite differently from what my district does and very, very differently from another friend's district. One complaint I read on EM is that the conceptual leaps are readily obvious to adults but not to kids. So that makes me wonder if HG+ kids do make those conceptual leaps that more avg kids don't make with the program. I agree the pace was much too slow for my son.
EM is similar to Sm in some ways but SM does not spiral the way EM does. EM is similar to Rightstart (which is now being used in several schools in the US after branching out of the homeschool market) which is very effective. Again, though it doesn't work w/ every kid and some parents aren't effective in teaching it.
