Not a lot of experience here, mainly some observations.
Generally, seems like a good idea; if you're in your bedroom with a gun in one hand and the phone in the other while someone's in the house, or in the extreme circumstance where you have to go tiptoeing through the house to find the bad guy, being able to light up the target without generally lighting the room would be a Good Thing(I'm not talking about outside the house/SHTF stuff here, just home defense). And there's lots of options now; guns with rails either from the factory or add-ons, lights with clamps for the barrel or receiver and so on.
I'd wanted to try some of these out, but I didn't want to spend a bunch on a Surefire or Streamlight setup without knowing if I'd like it. Then AIM Surplus showed up with this 9-led light, bracket & switch. For fifteen bucks, worth a try. So I ordered one, it came in the other day and so far, not bad.
It uses two CR123 batteries(not included) like the Surefire G2. Not quite as bright as the G2 I think, and the light has that blue tint, but quite bright; hit somebody in the face with this in a dim or dark room and they aren't going to see very well for a bit. And with LEDs instead of a bulb, the batteries should last longer. It has a tailswitch much like the Surefire, with a jack in the center where you plug in the switch. The bracket is the simple 'figure-8' type that'll clamp it onto almost anything. Since this was what I'd mostly wanted a light on, I mounted it on the magazine tube of the Benelli, offset to the right:
By the way, for sticking something like this switch to the forend? I had a package of the 3M Command Poster Strips to hang up a lightning-strike poster my daughter gave me; trimmed one to match the size of the switch and stuck it on with that. It's holding fine, and should come off no problem. I hope.
From some messing around the house, I'd say this or some similar rig is a damn good thing for a home-defense shotgun. Light available without taking a hand off the boomer, you can unplug the cord and the light stays on solid if you wish, and bright enough to both make aiming easy and make it less likely you'll have to shoot; bad guy who's blinded and under the gun might be less likely to violently dispute your objection to his freelance socialist ways.
Next time I hit the range I'll take this along and do some shooting, make sure the light will hold up under recoil.