Each chapter of your life has different friends, and they rarely come with. Maybe this one is reaching its end.
I would take the offer, better to move faster than others than waste time being told things you already know. I didn't learn anything until fifth grade. I was able to do algebra while the other kids were learning addition, and the reading and counting classes bored me out of my mind, but they just left me where I was and didn't take me out of the system.
However, be careful in social interactions. One mistake, or even just being manipulated, could haunt you for a while.
If you're really attached to your friends, though, just remember things change. I've been to five different schools in nine years, and the old friends make way for new ones. The more you reset, the more you know what you want out of a friendship, and the closer you get with new friends.