I see two issues with "gifted students" in modern education:
1) some school systems see them as critical to "raising up" other students around them, but I never see any analyses as to if this "holds down" the gifted student's development.
2) I've read that students learn a huge proportion of things from their peers. That implies that true gifted education involves comingling a sufficient population of gifted students of the same rough age range among each other.
3) gifted students really benefit from "gifted" teachers. They don't necessarily need deep PhDs in academic subjects, more they just need to be "broadly smart".
#1 sounds like it sucks for the gifted, especially with the substantial undercurrent of anti-intellectualism in American education and the specter of bullying. Maybe in a day of 7-8 classes you do gifted + nongifted intermixing for 1-2 classes at once.
#2 needs a sufficient population of gifted students
#3 is really hit or miss in schools
All three of those are why class conscious parents pay a lot of attention to the school district of a school, and are defensive of other students coming into "good" school districts. Also, per "The Bell Curve", smart people tend to be well-off, and so the specter of NIMBYism and housing exclusion rears its head over education.
Deep learning in traditional subjects is the default of gifted, but I agree that what is needed (as hinted at in breadth-smart teachers) is breadth-first learning. Because unfortunately gifted students have their passions decided for them: You're going to get good grades!
If my kid is gifted, and based on the inheritability of IQ, he probably will be, I'm not subjecting him to acceleration. It'll probably take some degree of home schooling instead.
The only acceleration I'd be in favor of is skipping Junior/Senior high school years and going part time to local colleges. Accelerate maybe 1-2 grades tops in specific things.