We have a bit of a different situation, because after one skip, we had the option and decided to commute 45 miles to a school for HG kids which is accelerated at least one year for all subjects. So our DS, who just turned 9, is in 4th grade doing 5th grade + work. We were lucky to have this option, since DS is small for his age to begin with, so we really didn't want to do another skip in our local district, even though that was necessary for academics. So instead we have an effectively twice-skipped kiddo. If you have any full-time GT or otherwise acceleration programs nearby, I think it's worth checking them out, especially if you are in a state where open enrollment across districts is a possibility.
That said, if the HG school weren't an option, we would have made a second skip work in our local district. The teachers and administration were willing to be flexible, which was great. I guess if you have a very flexible school, it might be worth considering subject accelerations, versus whole grade, so that your kiddo can stay with (closer to) agemates for things like phy ed. It may not be feasible with the way your school centers are set up, unless they are close together so you can commute.
How does your DS feel about another skip? When our DS skipped 1st grade, it meant a move to another school because of odd grade centers, so he was a little nervous, and then we moved him mid-year 2nd to a new school, which meant meeting all new people again. When he moved to 3rd grade in the same school with the same group of kids, he told us he was happy that he didn't have to move again. Depending on your kid, all the moving around can take a toll, but I think it's easier the younger they are. And the kids are overall happier when they are challenged and have more chances to be with kids with similar interests.
