Hope you don't mind me adding my thoughts to the discussion.
My ds is nearly 8 yo and has virtually no speech. He uses makaton quite well. He also is physically disabled. He goes to special school.
The headmistress did say that "life is mainstream" when my dh questioned the role of inclusion for children. However she, of course, has strong opinions for special school!
Me and dh thoughts are this: our ds is very secure in special schooling, his friends are all like him (but all different and individual too) and the children are all caring towards each other. The school understands their role in supporting the children and give them education geared to each individual based on their ability, so children who are coping well with a curriculum similar to mainstream have that level of education. Our ds could not cope with that level so he has the same curriculum but in a class geared towards their ability. The staff use makaton as a matter of course.
I never wanted my ds to attend mainstream school as I think his confidence would suffer. He would be included in the classroom but he would not be accessing the curriculum therefore he would struggle to make friends imo.
However our ds loves the company of children generally so we take him to things such as beavers and computer club. He is still sheltered (as these things are only 1 hour) but the other children enjoy our ds company. They are supervised by the leader so bullying etc cannot happen.
Dh and myself really feel comfortable that our ds is having good education in the day but accessing the "real world" for social occasions. He is learning to interact with his peers but in a relaxed way, not forced into it by having to attend mainstream ed.
What I have just written is my opinion, just to give food for thought. I fully understand parents who believe in mainstream ed for sn children - for some it works very well. But for children with no speech i think that is a severe disability and without speech, mainstream children just don't know how to approach the child - children do not know makaton for a start!
I would love to know your thoughts.