Thanks ladies, I appreciate your comments.
My guess, from what you've all said, is that 10y+5m will probably be fine for my dd to re-take the WISC. I just vaguely recall that some gifted kids start to ceiling out at some point and I couldn't remember when that was (and maybe "only MG" will make it ok)
I'm guessing that our psych will probably want to stick with the WISC as long as is reasonable, if only to make the scores more comparable (we're dealing with a language processing issue that caused dd's verbal score to drop more than a standard deviation in between the two times she's done the WISC; we're hoping that language therapy will help). Or, at least that's my thinking. The psych's recommendation list in the report said to retest in two or three years from last Dec, but next fall she'll be in fifth grade, time to apply to private middle schools (if we go that route). So a year from now I'll be needing the psych's advice. And, naturally, I can't wait to re-test to satisfy my crazy curiosity. For now I'll satisfy myself re: her progress with the school's MAP tests (wonder how accurate those are).