Thanks for the replies. We didn't bring in the Iowa Acceleration Scale Manual because we weren't advocating for whole grade skip (DS is anxious about it although he once suggested it himself). We did to the test, and DS scored on the high end of "good candidate" if I recall, even with the lower points due to the lack of school support for the idea.
I think I get a bit insecure when the school plays the "socialization" card because DS IS a little odd relative to the other kids. He has a sense of humor that most of the other kids don't get, and he can be obsessive about things the other kids couldn't care less about. BUT while he's not the most popular kid, he certainly plays well with the other kids in the team/scout/b'day party situations where I see him with them. And I feel like if he's happy with himself, then I'm happy for him. Frankly, neither DH nor I are particularly good social fits in most situations, and my poor apples probably didn't fall far from their parental tree.