A compromise may be to tell the school that you'd like to try it, but it needs to be flexible. If she feels stressed, pressured, or unhappy, then you'd like her moved back down.
DD10 has a full grade acceleration (she is finishing 5th grade) and then a subject acceleration for math.
Her math teacher recommended a further acceleration to Algebra next year for high school credit. They recommended an algebra readiness test. I said "no" and told them to put her in pre-algebra next year. I know my daughter and because she is 2e she would be stressed out by a high school level course (esp. at age 10 with a disability!).
My son, on the other hand...we have accelerated him 3 years for math and he has done fine. He is in third grade and goes to sixth grade for math. He loves it, and he loves being w/ the older kids. He is also 2e and there are some physical challenges (in his case it is his handwriting). But we are trying to find ways to work around it. What works for one kid is a bad idea for another. Sometimes you just need to try it and see how it goes.
