Dudesmummy - we have both boys in a very inclusive mainstream, which is half the reason why it's working for DS2 - the willing is there, as is the acceptance. Way back when he was 2, he started at the nursery on a pilot 2 year old placement and, as a boy who takes years to trust someone, hit it off immediately with the nursery worker who was assigned to him. He warmed to her and trusted her and she completely understood him and instinctively watched and followed and drew him out of himself and helped him to get so much out of being there. It took a fight by the school to keep her with him through the nursery phase, as the LA wanted to impose one of their own bank staff on him (he already had a statement, at this point), but the one they chose didn't turn up, as she didn't like the school (she'd previously been assigned to DS1 and it was a disaster because she always thought she knew best, but didn't).
So DS2 has stayed with this LSA, who wasn't highly qualified in the first place, but has been training alongside working with him and has been working with SALT, more recently and amassed an amazing amount of knowledge to add to her innate skills.
DS2 is still on P levels in year 3, so has a completely individualised learning program, which he'd also need in SS. He really benefits from the social side. We live in a village and everyone knows him and he plays with the other children at break. When he was younger, it was mostly older kids buddying up with him, but he now plays with some of the girls from his class. He's as pleased as punch when he meets a child he knows in the street.
We know that mainstream won't be appropriate for him forever - just as it's not for DS1. We'll cross that bridge when we come ot it, though.