My dd just finished 1st grade and was in 2nd grade EM all year. Her school claims that the 1st and 2nd grade curriculums are so close that bright students can skip 1st without issue.
Having said that, I am hating EM. I spend so much time going over things with dd. We're doing Singapore Math this summer just to make sure she understands good, old-fashioned math.

Think you can get your ds accelerated into 2nd grade math? Might be worth a shot.