I used to think they were an okay budget choice, if not ideal, and certainly not worthy of all the trash talking they get. I always say I like to admit to having been wrong because it means I learned something, and this is no exception. I've discovered I don't like them at all.
Over the past couple says, I've had a borrowed M&P which I've been experimenting with, unloaded with a Serpa Sportster. I'm doing a lot of studying for state mechanics licenses, and every time I need to take a break, I've been drawing, dry firing, re-holstering, and generally trying to get a feel for it.
3 times the M&P has become caught in the Serpa by my shirt tail in such a way that it makes the gun very difficult to get out. This I am guessing is less of an issue with different mounts, but I still don't like it. You could argue also that you simply have to be careful upon re-holstering. I don't like that concept, because there are many reported cases of re holstered handguns having to be re drawn because of an assailant getting back up after the defender thought they were down for good. This problem is non existent in my now over a year with my Safariland.
Once while doing a fairly fast draw I ended up with my finger in the trigger guard, with the gun pointed just barely past my leg. I do believe that in a high stress life and death situation, small little motor skills go straight out the window, and I now believe firmly that at least with some gun shapes, including this one, drawing fast from a Serpa could easily cost a user their knee cap.
While I still have yet to see an example of a verified real world case of a Serpa getting debris stuck behind the retention button in the course of real use, I nonetheless believe the other issues are serious enough that I can no longer recommend them. Not that I will argue with folks who use, like and trust them, but after experiencing this, I cannot endorse them at all. Safariland models can be had for as little as 20 dollars more, and that is now going to be my number one suggestion to people looking for retention.
In continuing my quest for knowledge, I'd love to hear about it if Serpa users wish to tell me any opposing viewpoints.