Wow, tough issue. When we moved, schools were definitely a consideration and we picked a district with a district wide gifted program to try and give DD a larger group of peers. This meant that all the highly gifted students were pulled together in one middle school and one high school. This has meant that the high school was easily able to accommodate a four year single subject acceleration. However, as others have pointed out, this has also meant a higher pressure high school with little time for outside activities. DD is now finishing up high school and says she would choose the program again. DH and I are more ambivalent.

If I had a 7th grader and could move anywhere, I would move where:
1) my family would be a good fit (lifestyle, politics, religion);
2) the schools are safe (you'll need to decide what this means to you);
3) there is "enough" math in the high school (for us this would have meant 3+ years beyond calculus);
4) admission to the high school is automatic or test based (we did try to enroll in a charter school and wound up #435 on the list when the incoming class size was 70);
5) there are other school districts close by that are also good.
6) school funding is adequate (yes, debatable)