I really dont ever plan on firing a single shot with the light attached....but if I do ever shoot with the light attached (which will only be in a case of self-defense) after the trial (if there is one) when I get my shotgun and light back, if the filament is broken I will send the light in to surefire and it will be replaced, they do after all have a "if it breaks, we'll fix it" policy.
I just can't justify spending $250 on a dedicated forend that will most likely never be needed, and if it is I'll most likely only need to fire 1 shot. If I do shoot in a SD situation, and the filament breaks I'll deal with it then. If there is an intruder, and I shoot, and I break the light, I will have positively identified the threat and the light did its job. The light is there to identify a possible intruder in your home, not engage in an extended 2 hour firefight (btw the batteries wear out in about an hour anyway, and I'd like to see a guy carry as many shotshells as it would take to wear a light out on his person....a shotgun is not a main battle weapon for more than one reason)
So as soon as my wife gets her doctorate and I have plenty of money I'll get the dedicated forend, and mount it on a 14" 870Police (perfect HD weapon IMO), but until then I am poor and will get by with my half-assed cheapo surefire rig