Um, okay, I TEACH "real world" tactics, and the FBI flashlight technique is ONE option. (Moving the light away from the body to search a dark space). I don't like it, because I am not a monstrously strong individual, and I find myself feeling unbalanced with my weak side arm held out way to one side, while trying to also consider the pistol in my strong hand only. YMMV.
The FUNDAMENTAL issue to remember when using a light and pistol is "LIGHT ON, SHOOT, LIGHT OFF, LATERAL MOVE"
I would LOVE to have a light on my issue pistol, because it frees one hand - "In the real world", I HAVE had a bad guy at gun point, with my flashlight in my hand, and realized" Now, how the frick do I operate my radio to let my partners know where I am? - I ended up proning the bad guy out, and holstering up, so that I could manipulate my radio, hoping that the flashlight would not let him be aware of my now holstered firearm. It worked - That time.
A light on a pistol is a great idea - but again, is only one tool in the toolbox, that your mind must learn how to employ.