In addition to Erick's comments, the Surefire weaponlights are much more recoil-proof than the MagLites. I have abused my fair share of MagLites (6D, 2D, 2AA) but the recoil of a 12 gauge can do some serious damage to a light, especially to a light that is going to be used in a life-or-death situation.
First, the Surefire weaponlights incorporate a shock-proof bezel, which uses a rubber grommet around the lamp to cushion the impact of the lamp against the lens or bezel. Without this grommet, the lamp can fail when it slams up against the bezel during recoil.
Second, the Surefire battery housing features a machined "shoulder" between the battery compartment and the lamp unit. Without this shoulder, the batteries can slam forward into the lamp unit, causing failure.
Third, the shrink-wrapped DL123AC unit used in the 6V Surefire Responders prevents the batteries from slamming against each other. The DL123AC uses a shock-buffer sandwich between the batteries and special contacts at the ultimate positive and negative terminals to protect the battery. Without this feature, the batteries can crunch into each other or the contacts with the lights, causing failure.
The MagLites do not incorporate any of the above features.
A weapon-mounted light on a longarm is essential, IMHO. Yes it can telegraph your position if used improperly. Proper training will fix that pronto.
Even assuming that a weaponlight would telegraph your location, I'd still opt for a light. Rule #3 (know your target and what is beyond it) applies in any situation, regardless of lighting.
Hope this helps,
Justin