I wish I was accelerated in elementary school. But there was no such choice. I did go to science and match school grades 5-8 and that was the best experience ever when it came to school. Not perfect but at least I had 30 kids in class who understood me and whom I understood.
... I was still among the smallest kids when I was 15, I was still just as clumsy and sometimes socially awkward as when I was 6 ... it wouldn't had mattered if I skipped a grade in the growth and social aspect ... but I would had been a lot less bored out of my mind the first 4 years. So, if we end up needed to accelerate, we will. DS4 is average size and pretty clumsy. Definitely not a sporty time, so won't matter with him ... DS2.5 is well built, above average size for his age and we have been calling him "bulldozer" since he started crawling ... even if he skips, he's probably still going to enjoy a spot on the wrestling team or football. He's got that strength, stubbornness and will in him. He will need to look after his older brother who will be picked on probably a lot. I'm guessing we'll spend a lot of time in the principals office with either one of them! lol ... but in our case it won't affect our decision to accelerate or not.