I wouldn't assume that she is MG just b/c that one set of scores say so. She sounds a lot like my eldest who also tested with an IQ within a point of your dd's at the same age. We had a similar situation where dd totally refused to complete part of the test and came out in the 25th percentile on that part (which would constitute bombing in my book -- lol!). Even the tester told us that she thought it was an underestimation given how high other parts of the test fell and other indicators.
While we've never retested IQ, I do believe my dd is HG b/c all other signs point to it. Her early development is spot on with your dd's even with the amazing small motor skills. She's consistently tested in the 99th percentile in everything on achievement tests except math (which falls in the mid-90s) even with being young for grade and even after skipping a grade. One test is... one test, one day.
That long aside apart, have you visited the GT magnet? If your dd is happy and has peers where she is, I'd be hesistant to jump at moving her. However, if she is going to go to the GT magnet middle school down the line my concern would be that she might not be performing as highly as she might otherwise be by that time if she's been underchallenged for most of elementary.
I'd do two things: visit the GT magnet and see whether you think it would be a good emotional & social fit for your dd, and, if she stays where she is, be a pain if you need to be and try to get better enrichment/acceleration options for your dd and her peers who need it. I'd ask for things like sending the group of kids who can handle it to the next grade up for literacy, an advanced spelling list for kids who get most of the std words correct on a pre-test, bringing some of the next grade level material for math or literacy into her classroom for the higher achieving kids, etc.
