Shot several thousand rounds through my M4 with RAS using a Surefire 9V with the Millenim LM90 lamp on a KAC surefire mount. Sure it's an older model, but the lamp is the same as the newer lights. Haven't had a problem yet, still bright as hell. Haven't had a bulb burst yet. Too bad the batteries don't last long and are expensive.
I've used a lot of surefires (6V Benelli forearm, 6V MP5 forearm, 6V hand gun lights, and 6V on .308s) and had no problems with the exception of the old surefire dedicated mount for the USPC. Caused the slide to lock back after about 5 shots on every mag. Surefire offered to replace the unit, but I was stubborn and kept it for parts since the new model was less expensive...