Thanks JTQ for the informative inputs. And you guessed it, I retired from le 22 years ago after working in this capacity for thirty years and my insistence on a thumb-break retention system is predicated on my experiences. I've done enough rolling around on the ground and scuffling with felons not wanting to return to prison to trust the thumb-break to keep my pistol in my hands. Some will argue that the thumb-break is too slow on the draw and I will admit that for some it's slower than other friction retention devices (some of which I've tried kept the gun in place if you tightened the adjustment screw enough but, in doing so, made the gun harder to jerk free from the holster) but fast enough for me.
Our bi-annual qualification drills required officers to draw a "Third Generation" Smith & Wesson 9mm, da pistol from a snapped secured thumb-break holster, worn on the strong side at the "4:00" position, under a jacket and fire two shots (da/sa) at a target ten yards distant within two seconds. Practice may not make perfect but it may make you good enough to survive the day. And I will concede that proficiency with a thumb-break holster may require more practice than might be needed for other types of retention systems.
