Haven't tried Magpul's, their 17s didn't lock the slide consistent for me.
I've been using ETS 22rnd mags, found one had a broken follower yesterday, warranty time for it I guess, should be somewhere between 2-3k on those three mags and a whole lotta dropping.
My observation is most seem to run factory mags with Taran Tactical extensions, I think they remain reloadable at 22, the ETS is sketchy crammed full fine at 21, I think I read about people occasionally needing to sand the Taran's to pass gauge, I need to find a mag gauge to see how the ETSs are.
3 is fine, before my optic died unbeknownst to me, yesterday, I'd never gone into a 3rd on a stage.