@Thomas,
How does the logic of my argument cause higher end kids to get lower grades? The regular ed kids set a benchmark - something for those with impulsive traits to aim for. Are you saying that regular ed kids are now going to start acting like they have Tourettes or dyslexia because one of their classmates does? Most 13 year-olds want to fit in, not stand out.
Perhaps I should be more specific since you used the work handicapped. I am working with students who have ADHD, some autism, specific trouble with math, reading, writing, or usually a combination of a few of the above. They aren't stupid. Most of them have intelligence in the normal range and a few have high intelligence. I'm not working with people with physical handicaps like those with low vision, wheelchairs, or mental disabilities that accompany more series learning disabilities. Those students are substantially more separate than the kids I work with. They attend most classes, but not all. They spend much more time outside of the mainstream classroom getting tailored help.
Regardless, the students I work with get individualized treatment from their peers. That's sort of my point. A kid bouncing off the walls and shouting out in class gets pretty much ignored because these kids have all been dealing with it for years. The class continues, there's no laughing and pointing (What goes on outside the class? I don't know). That being said, some of my kids are socially awkward. They're all 13 - many kids are awkward. Those kids, disability or not, are picked on. The kid getting bullied the most is one high-achieving, high stress, million-question-asking genius.
I have also read that same sex schools can be beneficial to kids. I don't know anything about it from personal experience.