I find it very interesting how people react to sports/social issues. I didn't want grade skips for many reasons, but those are certainly in the mix.
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I spend a lot of time wondering if I'm trying to protect something that's just not possible to protect with way out there kids and if, no matter what I do, DS will be ready for college at 11. It's hard to protect "normal" in that situation. But I'm sympathetic to people like your DH who want that for their kids. My kids aren't old enough to know how this will work out -- I can see us managing in an age-grade curriculum all the way through (in an HG school), or managing until 9 or 10 and then homeschooling a year or two and doing online college and high school things quite young, or just getting radical acceleration in one or two subjects and holding the rest at age-grade. I don't know how it will turn out or what's best for my kids, but I do think that things like sports and social fit can matter a lot for specific kids.
I agree completely, gratified, and have many of the same concerns, priorities, etc. for our kids that you have for yours. Sports and other competitions that require effort and practice matter to me. In fact, one of the biggest reasons we chose to homeschool was because we wanted to preserve the possibility of DS7's later returning to school at age level. Maybe in high school, where there are more options for accelerated learning, more access to college courses, etc.
Now that I know what I know about DS7, I'm also not sure that's possible or even reasonable. But my thought at the time was that if we homeschooled, we could go deeper into things and could maybe study things that weren't on the standard curriculum as a way to, well, really to *distract* DS7, and thus keep him fairly close to where his agemates are on the standard curriculum track, but without boring him. The more I see, the less realistic that notion seems.
I wish schools would go by age instead of by grade for some of those non-academic things, like sports. Or something more balanced. I don't expect my child to be a great athlete, but I do value the lessons that sports and other such competitive situations can teach a kid. I'd like him to get the chance to experience those things.
*sigh*