Another vote for considering the individual child! You know best what your child needs NOW. A lot can change in the next decade.

My ds was offered early admission to a (private) kindergarten. I turned it down, because he was socially immature. He had a good year socially, but hardly learned anything. I'm still not sure if that was the right choice, but-- we were lucky and got a "do-over"-- he was offered a grade skip in elementary (different private), and we took it. The skip was fine, socially and academically.
He's currently doing concurrent high school/community college. There are a decent number of teens there, so he doesn't stand out, and he's doing fine in classes.

If we hadn't taken the (second) skip, he'd be less than halfway through high school, bored and unhappy. He's happy with where he is now!