I use the Glock factory + extensions only. Never had a problem personally or from a customer. IE never pop off. Pierce, Scherrer have all had pop offs when dropped and just loaded. They don't seem to stay on 100%. Some work and some don't.
The + for Glocks with insert work great. They are supposed to add rounds to mag but what I have found is you can barely get 1 more in on a 27 and 2 more in on a 26. Full size guns tend to let 2 more go in but not always.
I also don't care about getting more rounds as I find them more useful on the 26 and 27 size guns. Never get used to having my pinky dangle and the Glock one adds just enough room to allow a perfect grip. I also use 3m tape on the front of extension to add a littel pinky bite to it. works perfectly.
If you're into duracoat, it tends to stick to it better than the metal parts. Go figure.