The training staff at the armed guard class I took insisted that the Serpas aren't safe. They believe that because there is a little hook that grabs the trigger GUARD, it will magically press the trigger through it's full stroke and discharge the pistol.
I realize people who teach these classes are typically very experienced with firearms, but from time to time, experts aren't just aren't experts. I own a Serpa holster and will be using it once my armed guard card comes back from the state. There's no way in hell I'm giving it up.
Look into the holster and you will see that yes, it does grab the gun by the trigger guard, but there's really no way for the pistol to be shoved in far enough to get to the trigger and press it all the way through. It's difficult to tell if it even touches the trigger with the gun in place (My example is for the P220/P226, don't know about other models).
I always listen to my instructors and do what they say in a class, but that doesn't mean that I'll believe everything they tell me and follow only what they say and not come up with any solutions of my own.
Mojave Desert's link describes an issue that is basically not an issue for me. Finger off the trigger no matter what holster is the golden rule. Doesn't matter if you have to hit a release near the area of the trigger, under no circumstances do you touch the trigger unless you intend to shoot. Remember, there are no accidents in the world of firearms.
I do appreciate Mojave Desert bringing that link up though, that's not something I've heard before. Or maybe that's what my instructors were trying to say about them and didn't communicate it effectively to me. I used it in my class. They knew I and another had them. Neither of us had any problems and they didn't ask us not to use them.
Bottom line, I have a Serpa and I won't have anything else for open carry. End of Story.