I was in a gifted program in grades 5-7, stopped going mainly because I had to travel to another school to attend and it was inconvenient.
I didn't "suffer" being in classes with folks who weren't at my level. The teaching staff did a great job and I never felt like I was being shortchanged. My undiagnosed ADHD means I goofed around a lot, but several of my friends told me after high school that they appreciated me because I helped them see learning from a different angle than their parents or the teachers.