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.
Sometimes the stuff we create in our own heads, while logical, isn't born out by facts. The proper way to carry a CT pistol in a holster, pocket holster, or secured in a vest compartment designed for a gun, is with the switch in the ON position. Same for a home SD gun. The switch in the ON position uses no battery life until the laster is activated when you grip the gun. Also have a set on a SIG P220 that I carry in an IWB. No issues accidentally activating the laser before I grip the pistol. Switch ON.
My spare is an S&W 640 with CT laser grip carried in a pocket holster or vest/coat pocket. Carried it very regularly for a number of years now. Only concern I've had is activating the laser sooner than I want by gripping the pistol too hard. A little practice handles that issue. cool:
I like the laser because the sights on a J-frame aren't the best in dim light. The laser works real well in a stairwell, pkg garage, or most places in doors during daylight hours. My P220 doesn't have night sights. It's an older model with a different front dovetail, and I haven't been able to find a sight for it. The white dot front, and the CT grips make it very versatile.