I'm not a huge fan of EDM. I have helped out in our 5th grade accel math classroom once a week for the past two years. I've taken home the teacher's manual a number of times to prepare for small-group work and there IS quite a bit on differentiation, but much more for the slower students. What there is for gifted is separate enough and complicated enough that I don't think most teachers have the time to do it.
I also was worried about CC, but I actually feel better now. I think it
will go slower in some aspects, but it focuses much more heavily on problem solving. Our principal showed this video when he presented it:
http://www.ted.com/talks/dan_meyer_math_curriculum_makeover.html (one both my husband and I have seen and love)
and he said that this was going to be our district's focus. The 5th grade teacher with whom I've worked for the past two years is part of our common core team for accel math and she has really changed the way she teaches. She starts off each class with problems similar to AoPS (although hers come from the NCTM high school problems) and she is really teaching the kids to problem solve. I've already noticed the difference in their perseverance.
I think that the CC *can* be a huge improvement, in spite of having some math concepts now taught in 3rd or 4th, say, being moved to 5th. When I first heard that I was thinking, "oh my gosh, it's already too slow - this is a nightmare!" But, if it really, truly does go deeper not wider (I know, that phrase probably seems meaningless we've heard it so many times)... well, I'm willing to withhold judgement.
Just fyi, our accel math is 8th grade algebra and our gifted math is 7th grade algebra. That's as good as it gets here.
