GATE Magnet
My child Artemisia, in second grade, just transferred to a GATE Magnet school three weeks ago. The school is basically just as you described, with a reputation for having a student population that makes the teachers want to tear their hair out. It is also a Title I school, which means that the population has not met their Adequate Yearly Progress requirements for a few years. Not sure if that has something to do with how the school got the GATE funding?
In any case, the school is well-funded. The second grade GATE students are going on six field trips this year; there are 3 separate instructors for computers/tech, science lab, and music/choir/drama. These features used to come standard when I was in school. Now at the regular public schools, especially if they don't have their AYP, it is a sad state of affairs. There is no funding for this "extra" stuff, and the schools are only interested in standardized testing in Math and Reading. The state paid for the kids last year at the regular public school for the kids to have science books, but not until after year-end standardized testing did the teacher crack them open. It was the last week of school at that point; not too much time remained to get into things so the teacher told the kids that the best example of the gas phase was farts. Grrr! No wonder my kid starting acting up in the last couple months of first grade if that's the level on which they were working. But I digress...
Besides the scope of the curriculum, her new school gives the kids a lot more freedom even though it is accelerated. They are also given more responsibility. My daughter is responsible for pulling & copying down her own homework, and it is due daily. It is not really that much more work than she had before, but it is more thought-provoking. The standards by which the kids are tested are the same for the entire second grade. The biggest thing about this GATE program is that they demand parent involvement. There will be a research project and a science fair toward year's end; it will be a lot of work. I could tell that it was a good school when I met with the Dean and visited the campus. The teacher is a little overbearing but I think she is just the right one to deal with a class of gifted students! Just try to get a feel for the people who are running the place. I was worried about my child being antagonized by "bad" kids from the school but she had not been subjected to any feeling of segregation. The all eat lunch, go to recess, and have other activities together. The niceness may change as they get older, but at this point I think kids are kids and it is working out great.
It is a lot of extra work having a gifted kid anyway, so I figure it's worth working with these people from the school district if they are willing to help my little girl grow.

Give it some serious thought, and be ready to put in some extra work. There are costs and benefits. With the sorry state our schools are in these days, I did not really feel like it was an option to leave my kid in general instruction.
Good luck!