For years I have owned a G21 with thumb safety
I own a Glock 21 which is my one and only do-it-all pistol (spouse mandated limit).
I installed a Cominolli safety on the pistol years ago, and fired 1000s of rounds since without a hiccup. Glock still honors the warranty on a pistol with a Cominolli safety on it. I also intalled "the gadget" as a substitute for the back plate. Keeping one's thumb on "the gadget" while holstering is very much like pressing down on the hammer of a DA pistol with the thumb, in that the down pressure will prevent the trigger from being depressed.
Here is AIWB reholstering process:
a) bending backwards, hip thrust forwards, right leg back and a holster that does not deform (Garrett Silent Thunder) = no self muzzling.
b) Cominolli safety on and/or thumb pressing on "the gadget" = no negligent discharge (even if trigger is being actuated somehow)
a) + b) = no Glock leg
Negligent discharge + a) = no Glock leg
Self muzzling + b) = no Glock leg
Probability of Glock leg =
Chance of: depressing the trigger + also not doing a) + also not doing b) = 0.00000000001 %
The only way it could be lower is with no round in the chamber.
Also chance of: needing to fire a shot + not disengaging thumb safety = chance of doing so with a 1911 = (almost) chance of forgetting to depress the trigger itself.
I know many will not agree with this, but the set-up works flawlessly and I could not find another pistol that off the shelf would offer these characteristics.
EAA (Tanfoglio) Witness comes close, but does not allow for the versatility of using short mags for concealment and longer mags for more ammo capacity like the Glock does.
The pistol is still Glock reliable!