Here's where I have to stand down. I couldn't possibly comment on how best to integrate autistic children. I think it's going to be a challenge, however, regardless of whether you have one standard of education or multiple streams. Ultimately, you have to account for impairments to education.

Perhaps the issue at hand is where you draw the line on educational impairment. Personally, I don't see any method as being capable of identifying impairment/educational limits between superior and average students. There are ways of identifying learning disabilities or impairments like autism but and clearly identifying those from non-impaired students, but I wouldn't be comfortable saying that certain children simply aren't as smart as other kids so let's not challenge them.

I can only speak anecdotally, of course, I was a solid "C" student all through school and didn't turn "on" until grade 10 at which point I became a high performer and finished high-school a straight "A" student. For me it was motivation and peer influence. That doesn't mean all kids can be turned on like that but if I had been streamed (and they tried to) into general curriculum I'd have never gone to University.