The Serpa is kinda bulky for concealed carry compared to some others. Having carried for 28 years daily, the Serpa is great for duty or a cop or soldier who is going to be running or worried about gun retention with bad guys. These are pros who are paid to run TOWARD the bad guy and engage. If you fail to PRACTICE PRACTICE PRACTICE to press the release button while drawing under stress, you may fail as a civilian to get the gun out when you need it. Only constant practice with a safety holster will develop that muscle memory. Most civilians don't or can't afford to do that amount of draw and fire practice, or don't have a range that allows shooting from a holster.
I have used a Fobus paddle holster (not the Roto) for my Glock 19 since 1999. Same holster daily on and off duty concealed. It retains well even running and conceals well. No gimmicks, and as a civilian who is not exposing your gun and not wrestling with or chasing bad guys, a good choice. I had my doubts when I first got it, but it has stood up well. I tried Galco's similar holster, but their design allows the holster to rock fore and aft because of only one stud on the waist paddle. Fobus has two and stays where you put is. Even without a belt, I have never had the holster come off when drawing the gun.