This Pelican M6 is a very interesting looking light. I have toyed with it and loved it. The only thing that kept me from buying is that there are a lot of reports the bulb blows within a few battery change. I do not know if this is due to bad design or poor usage. For any fresh incandecent light to last long, you must at least run it on a set of fresh batteries continuously for 15-30 mins at least. This will soften the filament and make it more durable after it cools down.
I have the Surefire run through at least 5 boxes of batteries and the bulb is still very clean without any trace of darkening on the glass.