The Huffington Post has an essay here by a mother explaining that her two special ed. children--who both have intellectual disabilities--do better in small, special ed. classrooms rather than mainstreamed into regular classes.
She discusses an issue in education that is very interesting, and very topical. It's a little discussed issue that special ed. costs are a huge part of any school budget, and are rising rapidly, especially now, I would guess, with all of the children on the autism spectrum. The original federal law said that children should be mainstreamed whenever possible. This was written in because years ago children who were disciplinary problems were warehoused in spec. classrooms, and didn't receive much in the way of an education. All of that is changed now. Most children on ed plans can be taught in regular classrooms, often with the help of aides. But some children who have severe disabilities do better in small classrooms set up especially for them, with a special ed. teacher. The problem is that separate classrooms are very expensive, and school districts often fight having to move children to such a classroom, especially if the district is too small to have an appropriate classroom, and has to pay to have the student educated in a private school.
Personally, I think we pay now or we pay later. I think every child deserves the very best education possible, whether that's in a mainstream classroom, or a separate one.