Hi Cym,
We had a very similar experience with grade skipping and our now 12 year old. He started K at 4 making the cut off by 2 weeks. By 4th grade it was clear that he needed more acceleration. His elementary school went to 5th grade with the 6th grade in the middle school. We decided, after a lot of meetings with his principal and the principal of the Middle school, that he would skip 5th grade. Doing this made it a little easier since all of the 6th graders would be new to the school and comming from 4 different schools, there were alot of kids who didn't know each other. In hindsight I wish we had skipped him earlier in grade school so that he had a larger friend base. He is also on the small side although average for his age. Eighth grade has been very good for him socially. Overall the skip was good but still not enough. The school has been very stubborn about anymore advancement. We had to start homeschooling him this year. He will enter the High School next fall at 12 and will do dual-enrollment with a combination of High School, homeschool and College. It's been challenging for me; I feel as though I have spent the entire school year running behind him just trying to keep up. (I'm still not sure who got homeschooled?) Like your son, he is very positive about the grade skip. Since most of the kids his age are in 6th grade now, he sometimes socializes with them and he will come home and say that he can't imagine being in 6th grade.
Eileen