I have CT sights on 3 of my handguns and they do work. The bullet goes where the dot is.
I do not keep my CTs ready to go. I have to turn the switch on before the little side switch will activate the beam.
I would have two concerns with using them on a daily carry gun.
1) If the master switch is on, you might have something press the little switch that would drain the battery.
2) In a real emergency, you might not have time to turn the master switch on which would negate the reason for the sight in the first place.
I use them for my home protection gun. I might need them and I might not depending on the situation.
You ask a very good question. Others will chime in shortly.
Normally, for carry in my truck, I use a G30 or a G19 and I don't have CT sights on either one.