I use a TLR1-S ( just a light ) on my XD-m 9.
I have the CT LightGuard ( laser ) on Taurus PT709 Slim and it's fine. There is no thinking with it. As soon as you grip it, the laser emits. It's not so much for use I guess defensively sighting other than intimidation?
Even a defensive weapon light, on gun, my instructor advises against. He is for a hand light w/strobe. To spot light away from the body at different locations, always moving. (ex - home defense) If an intruder has a gun, they more than likely will shoot toward the light. But I know the light can/will temporarily blind or disorient.
But yep - I agree in a defensive quick draw it's all POI aiming, no wait for the dot to get on "X" body part.