I am not a tactical oper8t0r by any means but I do have a few general comments based on my experieces... I actually got one primarily for airsoft since I regularly use my light in that environment (that, and you cant OC in Illinois). I bought it to replace my Serpas.
1) They work fine on both Gen3 and Gen4 Glocks.
2) The retention is fantastic. The GunClip is almost always on my chest and sometimes on my belt. Never came undone even with some good spills on my part. The weapon is retained fairly well even when the holster is unclipped.
3) Retrieving the weapon is easy enough to get used to. Not as fast as a Serpa but not as cumbersome as I expected it to be.
4) When the holster is on a belt and your weapon is drawn, the clip/flaps will flop around a bit as you move. On my chest, gravity keeps them in place. This is a non-issue for 100% of the time the weapon is holstered and hardly so when drawn.
5) Getting the weapon back in the holster, especially with gloves, can be a little cumbersome especially if you cant see the GunClip. Its not hard, necessarily, but its not a simple *push* *click* that you get with tension holster.
6) There are a fuck ton of angles you can mount it at. Reducing the tension on a screw allows you to rotate the holster relative to the base. This may be common in OWB holsters but Ive only otherwise used a Serpa (which has a few pre-selected orientations).
If we could OC here, I would consider using it. It does look intimidating between its design and exposing so much of the gun and weapon light but maybe thats a good thing to some.