indigo, as usual, has already covered many of the crowdsourced and official state references.
On the anecdotal side, yes, I do know several people who have grade accelerated into being 12 or younger while enrolled in high school or higher (some accelerated earlier to reach that point), both males and females. Of course there are adjustments, and of course, some of them are more challenging than others, as is the case for nearly all educational solutions for HG+ children. On balance, though, I think all of them view their path as net positive.
I would like to call this a positive, but some others might view it as a negative, so I think we'll just leave it as a value-free phenomenon: being an HG preteen in the teen world of high school can allow an individual to observe the adolescent social-emotional maturation process (Mating Rituals of the American Teenager, among other things) somewhat more objectively, prior to personally experiencing hormone-driven emotional volatility, and while still slightly outside of the stream.
I expect you already have some sense of the intellectual/academic positives, or you wouldn't be entertaining this idea. Learning work ethic and healthy failure are equally, if not more, important possible benefits.
Sports are generally age-limited at the upper end. So if you are good enough, you can "play up", but you generally can't play "down", with a lower age group. Hence the age brackets named "U[age]" or "[age]U". Some sports allow you to continue playing with your age group, even when grade skipped, if you can document that you have historically played by age, not grade.
