Something that struck me that she may get out of this different model of socialization is the ability to make all sorts of friends, with all sorts of different people. I think that often in a larger classroom situation that it can be easy for children to fall into groups of friends with similar likes and dislikes, similar favourite games, etc. Amelia has the opportunity to learn how to make friends with children that she otherwise might not. For example, there is a boy in our friend's class who is also in one of the out of school classes with Amelia. I know from my adult conversations that this child is 'the problem child' in his class, and that his classmates look upon him this way. There are many of his behaviours that I don't like, and that I have a hard time being around. But Amelia takes them in stride, and considers him a friend. I think that if she were in this class, it would be hard for her to have this same friendship. Partly because she would be exposed his behaviour for longer, but also because she would probably be with a group of girls who like to read and play princess, and none of them would want to be around this boy either. She even knows that it's hard for him and he gets in trouble in their class together, but this doesn't impact her opinion of him. I can't say that one way or another is better, I just think that it's neat that Amelia is free to be friends with someone she might not otherwise.
I think even with less extreme examples of difference, it's great that Amelia gets to learn how to be friends with all sorts of different people; she can play hockey with some of the boys, or farm with the older kids, or just run around with the little boys. With our close friends L and A, she knows what sort of play they do well together, even though, again, in a straight school setting, she might not be friends with L.
To me, that type of socialization is important in the "real world", yes, there are people that we are naturally going to be friends with and want to hang out with, but the real skill is to be able to be comfortable being friends with people who are very different from ourselves. To be able to understand how to be able to work with and have fun with people that might not be our 'type'. I hope that this kind of socialization continues for my children no matter what path we go.