Hi shellymos,
I think that the elementary school years are tough for some EG/PG kids in the regular school setting, no matter how fabulous your school is at identifying and differentiating for your kiddo (and your school system is really wonderful). Like CFK said, sometimes the base grade just becomes too far away from the actual level where your DC needs to be, and if it gets to the point that the only things that your child can benefit from in said base grade are some of the specials and gym, you've got a lot to think about.
I believe that your school situation is also complicated by having grade-based centers, so your DS would be beyond some of the materials that they have at the base school. Would another skip help this situation? Is there a way that your DS can join the lower grades for gym?
My DS is not really in the same situation as yours, because your DS seems to like to take off like a rocket. But we have in effect 2 years of a grade skip (DS skipped 1st this year, and then last month transferred to a school for HG kids that works a year ahead and also provides differentiation). The difference has been amazing for us, because our DS is challenged (for now), whereas he was in many pullouts at the old 2nd grade class and still needed more. So a change in base for us has worked well, but it's apples and oranges because DS is still just a year to a year and a half younger than the kids in his current school, since the second "skip" was to HG school rather than a traditional grade. If we had stayed in our local district, I feel fairly confident that we would have had to do another traditional grade skip.
I know that I don't have useful advice, but I do feel for you! Good luck in your decision making.
