Picked up the Polytac yesterday, got it as an early Christmas present from a friend. I'm very happy with it, it's much brighter than I was expecting and doesn't seem to heat up much. On full brightness it will light up street signs about 400 yards down the street. Being on the other end feels a bit like staring directly into a stick welding arc on 200 amps, minus the itchiness that comes with UV exposure. Battery life remains to be seen, according to Streamlight it will start to sag after about 1hr on full.
Took me forever to find a mount I liked though. I wanted something I could bolt on to my forend to avoid having to clamp the magazine, but I also wanted the light mounted further forward. NCStar makes a nice looking MLOK cantilever mount so I ordered one last night after struggling to find one in stock. There's enough space inside my forend to fit the MLOK mounting nuts, so I'll drill some holes and bolt it on with some JB Weld for good measure.