I'd always consider individual IQ scores over group achievement tests and, like you, haven't been the biggest fan of the CogAT for identifying gifted kids b/c I, too, have seen CogAT scores that haven't lined up very well with IQ scores in my kids and others.
This probably won't be a totally popular view, but I would also agree that I'd put more weight on the more recent IQ test scores than the older ones especially b/c her performance seems more in line with the more recent scores. Also, although I certainly wouldn't agree that kids level out by 3rd grade if they are actually gifted, I do agree that IQ scores can and do change over time especially in young children. See, for example, this article:
http://faculty.education.uiowa.edu/dlohman/pdf/Gifted_Today.pdfThe WISC scores are still gifted and I would certainly still consider a child with a GAI on the WISC of 132 to be a gifted child. She just may be a more moderately gifted child than a highly gifted child unless there is something else going on.
If you suspect 2e issues, then all bets are off the table. I would never say that a child has to be homeschooled solely based on IQ #s (although we've homeschooled ourselves in the past), either. If school isn't a fit or homeschooling is the family's preference, then that's when the child should be homeschooled, not just b/c s/he has hit some specific # on an IQ test. My one non-2e HG child is doing okay in public school w/ a grade skip. (We don't have full time gifted programming available.)
Your dd does seem to lean toward math and visual spatial as strengths. Does her school seem to be doing enough for her in that area that she has to work to do well? I'd say that the ideal spot is where she can maintain good grades but has to work hard for those grades, not just show up.
