Without question, the easiest way to engage targets in low-light is with a weapon-mounted light. This is mostly because you don’t have to coordinate the direction the light you are holding in one hand with the direction you are pointing the gun in the other hand—mount the light to the gun and everything is simplified.
SureFire’s X400 can be operated with the rotating switch at the rear of the unit or with the grip extension, which is available for a variety of popular handguns. This gives you the option of deciding how you want to control your weapon-mounted light.
Well, almost. Engaging targets is not your only consideration, unless you are participating in some sort of sport shooting competition. When operating in the real world and using a firearm as a defensive weapon, you need to be able to look into the darkness without endangering everything you see. The most important rule of gun safety is to never point a gun at anything you do not wish to destroy, kill or at least poke a hole through. If you are searching in the dark with a weapon-mounted light you will likely violate this safety rule. You might think this is not an important consideration if you are responding to a home invasion, but what if it’s just your teenage daughter coming in late from a date?
The other problem with weapon-mounted lights is that, especially when attached to handguns, they add weight and bulk. They also require specialized holsters suitable for handguns with weapon-mounted lights attached, and many of these are better suited for duty use than general, everyday concealed carry.