My DD's magnet is on the smaller side, so she is developing long-term relationships for sure. If she had other close friends whom I could rely on to stay in our lives, it would be less of a concern for me. But this hasn't been the case for us. We have "casual" friends whom we see fairly regularly and whom she considers friends, but she hadn't really deeply connected with other children till the magnet.
And I also agree with mon about the leadership issue. However, I think it's possible to find ways to handle this...with effort.
Another concern for me is the ability to take direction from a variety of adults in a variety of higher-stakes situations. Taking adult direction is hard for my DD, so this is important!
(A great homeschooling coop could solve this problem, too. And there are other ways. But it looks daunting to me personally. )
