I have 2 kids who have been identified as gifted. We've moved and traveled a bit, so they have experienced different educational settings over the course of their schooling.
They both attended Montessori programs from age 2 1/2 and they thrived there. The child-centred approach, freedom to choose from a broad range of activities including practical life, as well as more academic activities, and to progress at their own pace really suited them. Since there is no expectation that all children will work at the same level or develop at the same pace and there is no grading or testing, there was no problem with fitting in.
After Montessori, they both attended public school programs for awhile where they received a bunch of different accommodations (cluster grouping with other advanced students, in-class differentiation of work and assignments, subject acceleration) that worked fairly well. It wasn't always perfect, but the schools and the teachers were willing to try and that counted for a lot. We found less accommodation in the private schools, where there was an attitude that all of the students were advanced. We also homeschooled for awhile, but my kids like attending formal school programs. They enjoy engaging with other students and learning collaboratively. They missed being a part of a school community and asked to return.
By middle school, they both attended congregated gifted programs. Their middle school had about 200 gifted students. It was a terrific experience. The school offered challenging academics, a good arts program and lots of extra-curricular sports and other activities. They were motivated and inspired by the other gifted students and the teachers used a variety of methods to keep the kids engaged.
They are back in the public system in high school, attending a specialized, selective performing arts school (admission by audition only). Academically, the arts students perform well on standardized tests (best scores in our city), but I actually think the courses don't compare favourably to the high school congregated gifted program. I think my kids would be more challenged academically if they had stayed in the gifted program. They love the arts focus at their school though and they are engaged and happy at school, so it's all good.
A lot will depend on the quality of schools available in your community. Some places are better served than others. Some schools have better administrations and teachers than others, even if the "gifted" or "enriched" programs don't appear as good on paper. You really have to get to know the school community and figure out whether it will suit your child.
I have discovered that in any school setting, the parents and the student are ultimately responsible for the learning that happens. In a bad situation, it's important to intervene and find solutions to improve the situation, but it's also important to work on tolerance, flexibility and coping skills in your child too. EQ is as important as IQ - i.e. developing emotional intelligence and maturity is as important as developing intellectually. That can be difficult for some gifted students who have issues with overexcitability, sensitivity and perfectionistic tendencies. It's easy to overlook these issues if you only focus on the academics offered by a school.