I question When does it become more important to accelerate rather than enrich, if ever? ... I just want him to be happy.
What's great about acceleration, is that it get's kids who need to learn in groups to be with other groups of kids who are at a similar 'readiness level.' It doesn't solve the rate problem, or the asymetry problem. One one hand your son is happy to learn independently, but I think he would have more overall social happiness if he were with older kids. Acceleration isn't the best answer, it's just the cheapest answer for folks who aren't near programs for PG kids, can't afford to homeschool, etc. But, having said all that, it does work pretty well for lots of kids. Not all - certainly!
Best Wishes,
Grinity
