I have been so on the fence about what to do about dd6 and wondering if I was crazy to think she was gifted, even >MG, but these anecdotes are making me think it is worthwhile to test this spring rather than waiting another year or two even if might be more accurate in the future. I had been attributing some of the breakdowns to adoption related issues but I do think some of i tis due to poor academic fit, psychomotor OE, and the amt. of effort it takes for her to conform at school.
Re: grade skips, I think the Iowa Acceleration Scale is a good tool to remove bias and see if the kid is a good candidate or not. Sometimes maturity improves when around older kids.