i don't remember the brand, sorry. It was 4-5 years ago when I ran them through a shotgun class on my M1 S90. Day 1 went well, but as the class progressed, they became less stable for me. After the class, I removed it, gave it to a friend and put on a rigid carrier. I've never looked back.
at the risk of sounding like a specwar-wannabe, they are probably just fine for the vast majority of uses. If I am ever doing weapons transition "for real" while rolling around in the dirt and brush, I'm having a really bad day. If one is not making frequent and repeated contact with the ground, it's likely they will stay right where they were placed. but as I say, I did have that experience and the experience stuck with me (no velcro pun intended...).