My wee difficult child is in Montessori school. He started there a year ago and is in kindergarten.
We debated between attempting public and this school for some time. Thankfully, the therapists working with him were glad to visit public school together, and they both, independantly, identified a whole host of situations that were disaster-set-ups for difficult child. One teacher, 26 kids, and a "floating" aid who worked in 5 classrooms, so she wasn't even always present. Twice a week they have "group sing", where all 125 kindergarteners get together in a room the size of half a gym and sing for an hour, whlie standing and "dancing" softly. (A - my difficult child refused music class at the early intervention school... B - dancing "softly" is not even on his radar). Gym class - 50 kids, 1 teacher... Recess 125 kids, 2 teachers... I could go on and on.
Anyway, Montessori has worked well so far. He's allowed to move about while he works, and that, in itself, is the single biggest reason I think its working out for him. I don't know what your difficult child's issues are, but I'd encourage you to investigate. I thought Montessori was a type of parachoial school and almost bypassed every even looking at it. (and certainly nothing wrong with parochial schools - if we had one that was a better fit for difficult child, he'd be going there instead).