Generally, I’m not a fan of lights on guns that will be carried IWB. Light bearing holsters are all pretty huge and also add safety risks as the holster mouths generally allow large gaps exposing the trigger more than non-light options.
The biggest benefit I’ve found to having a light on a pistol is the reduced recoil associated with hanging 2-4oz off the end of the muzzle. A large WML works at least as good as most compensators do without diminishing the reliability of the gun. Competition shooters exploit this often and very heavy ‘pistol lights’ exist for gaming purposes.
In all the low light matches classes and range days I’ve done I’ve found that for all things EXCEPT shooting, illumination from a WML is worse- it adds MUCH ND risk.
SIGNIFICANT and additional ongoing training is needed to offset the risks added by carrying a WML. Most would do better if they avoided the light altogether and just kept training the fundamentals of shooting and fighting. I know of 3 tragedies where cops shot people they didn’t intend to shoot while trying to turn on a flashlight that was attached to a gun. Google ‘slip and capture’ errors for more on that.
Inside the US, It’s so rare to be in darkness that requires light to shoot that I find the drawbacks of carrying a WML to be much more than the benefits a WML provides. There are PLENTY of areas/times in the US where it is dark enough to need light to IDENTIFY a trarget, but few that require more light while actually shooting. It’s hard to see a gun in the hands of a dimly illuminated target at distances that a WML could sufficiently illuminate. It’s EASY to make center mass hits on a that same dimly illuminated target at those same distances without additional light. I need the light to DECIDE to shoot. I need much less to shoot or see the target drop or create distance.
Most of the time you will NEED or want light, you will not have justification to be holding a drawn gun. Even with the gun out, you don’t want to be in a place where you need to point a gun at an unidentified person. They are non-threats until they are threats.
Handheld lights work better for all my needs. A headlamp works better. Turning on the lights works best.