Could you go and observe the all-autistic class they're recommending, assuming you haven't already? I imagine a lot depends on the specifics.
I am planning on taking a look at the class once I know what the actual school recommendation will be.
The big reservation I have is I feel like we would be taking a step BACK if he went to all autistic class. From what I was told (and again, I'd see the true reality once I'd go in to observe) they concentrate a lot on visual communication tools and I'd rather not go there. While DS isn't communicating much (as in having actual conversation), he has about 600-700 words vocabulary (growing every day ... all words that he understands and can read most of them) and is capable of using the words (when he feels like it ... mainly talking to himself when nobody knows about it :)). He's made a huge jump in communication the last 2-3 months (went from just screaming / crying when frustrated to taking me to what he wants, showing me what he wants and using words to let me know what he wants) ... I want to move forward, not backward ... if that make sense? That's why I think that being in a normal special ed class with kids with various little issues (speech, slight developmental delays, etc.) with an aid would make more sense. These are small preschool classes that teach kids all the tools to be able to go to regular K. I went to observe 3 of these classes and in 2 I saw kids with bigger delays than my son's ... Dawn syndrome and some other.
We have a 6 months Early Intervention review coming up on Monday so I'll see what his therapists suggest. They all have worked with him for the last 6 months or so and have come to know him quite well by now, so I do value their opinion a lot too.