I've owned this holster for about 4 years. The thumb release is the best I've found. I've tried other brands of thumb release holsters and this is the most natural i have found. Never had problems with it locking and being secure. Mine if for the Sig 226. I'm now looking for one that fits the Sig 320. I've e-mailed asking if they are going to make one. No word yet.
I went to the 511 store in Riverside and was looking at the Thumbdrive holster and decoded to bring my 226 to make sure it fit well. The workers grabbed a Right handed holster for me and I pulled out my weapon (cleared and empty of course) and put it into the holster.
The Thumbdrive locking mechanism did not engage at all. I was able to draw the weapon with no resistance and without pressing the thumb release.
We thought it might be a bad holster, so they grabbed the other 2 on the rack and we tried all of them. None of the holsters actually locked my weapon in the holster. The concept of this holster is good because it doesn't leave the release on the outside of the holster like the Blackhawk Serra, but the implementation is obviously flawed. I don't know if Bladetech, (who actually makes this for 511) is at fault or if the system was just never tested on the 226 even though it is listed as supported.
If the bugs are worked out, I definitely want one, but until I can be assured that the holster is secure and will not allow for a no resistance draw, I can't purchase this and in good faith can't recommend to others either.