I was homeshooled growing up.  It enabled me to learn at the pace I wanted: fast.  I finished highschool in 9 month and in college people called me Doogie because I wasn't old enough to drive.  Although I felt out of place, I wouldn't trade it for the world.

I would recommend NOT advancing a child past their age group.  I had no preparation for college because I didn't know how to manage my time.  Classroom leaning is wasteful but necessary to graduate.  I thought I could apply my self-paced education to the college world. It wasn't pretty.