Just got done doing our night qual tonight, and I'm not very impressed with the M3. Out of the 4 of that used them, we all had problems with them going out. They would just go out in the middle of shooting. Some of them would come back, and others didn't. Mine is still acting up. If I tap the light it'll sometimes work. I've had mine for a couple of years now, and haven't had as many problems as I had tonight.
I can't wait for Sure Fire to come out with their new Handgun Lights. I know they're more money, but they're worth it. I've got an E2, 9AN, and a M97 mounted on my rifle and haven't had any problems with them.
Anyone else had similar problems? To any considering the M3 as a cheaper alternative to the Sure Fire, you'll get just what you're looking for, a Cheaper Light.