I think these are good points, but I don't buy that these are true of a majority of gifted programs. Enough of my friends were also gifted (or we became friends because we were in the same problem) that I didn't feel the separation you describe. In fact, it was a relief to get out of classroom settings where peers valued social performance over intellectual performance. Gifted gave us a space where I could be comfortably awkward.

I also had experiences with mixed skill level classrooms and frequently found myself paired with students who didn't want support -- either from myself, other students, or the teacher. They didn't want to be in a classroom of any kind. I can imagine environments where this does work, but it freaks me out a little bit that you say you're certain this works.

As an additional anecdote, my son loves his gifted classes. But similar to myself, that's where his friends are.

I wonder if we'd both agree that kids' social environment is more important than the structure of any particular learning program?