I do not allow the Serpa for several reasons. I ran a class right after they came out. This course involved some ground fighting techniques. A pebble lodged in the release mechanism of the holster and that gun would not come out for love nor money.
Secondly, to release the mechanism you have to mash down on a button with your trigger finger. In a stress situation it is very, very easy to continue that mash onto the trigger, and prematurely fire a bullet.
Third, I don't advocate retention systems for concealed carry. I don't need to prevent my pistol from being taken from me if no one knows I have it. (Though a good holster does need to retain your weapon if you're tussling on the ground.) I have seen people literally try to lift themselves off the ground while drawing from these holsters...because they didn't release the mechanism.
Finally, some of these holsters, if you put the gun in backwards, will not release the weapon. Why would you put the weapon into the holster backwards? That is a technique for reloading the pistol if you are reduced to having just your weak hand.
At any rate, I'm not the only instructor that is banning the Serpa from their courses. A little "Googlefu" will reveal that is pretty much a standard policy.
