Many parents prefer inclusion as a compromise between a special needs classroom and unsupported mainstreaming. And, indeed, inclusion can be a terrific option in the right setting.
There are, however, a few potential down sides to inclusion. For example, autistic children in a typical classroom may suffer from bullying and teasing, as kids will notice they are being treated differently. If the child has a one-on-one aide, the teacher may see the autistic child as "taken care of" and focus her attention on other students. If the child has an adapted curriculum, it may actually be taught to him by the aide and not the trained, credentialed teacher.
Department of Elementary and Secondary Education. Questions and answers about no child left behind: update 2004.
Hayes, N. To accommodate, to modify, and to know the difference: determining placement of a child in special education or A504. New Horizons for Learning, 2000.
Iovannone, R., Dunlap, G., Huber, H., & Kincaid, D. Effective educational practices for students with autism spectrum disorders. Focus on autism & other developmental disabilities, 18(3), 150-166 2003.