I just looked at this question myself. From the posts I've read the ultrastinger will out throw all the surefire's (turbohead or not) except the 10x for pure distance.
Since I was looking for something to be a long distance unit that was the one I leaned to. I just picked up a M3 and it's a great light, love it. I have no doubt the M3 will take more abuse, but I don't really require that of this particular light. If it was going to be a duty light or a EDC light then sure.
I do like the pyrex lens, smaller size of the M3T but for me initial cost and run cost were issues as well and the ultrastinger has it beat hands down there. Since it's less than half the price and much cheaper to run. It's also nice that dare I say it I don't think there is a surefire dealer in this state. However, we have several streamlight dealers so getting parts in a pinch is easy as well.
For me it basically came down to that the M3T with it's larger turbo head would not be a every day carry item anyway, so the extra size of the ultrastinger was not a issue for me. That and with the turbo head the whole idea is the tightest long distance throw beam you can get. Well the ultrastinger beats it there too. I also liked that the ultrastinger had a focus option so if needed it could do a wider area duty as well. Though granted probably without as smooth of a beam.
On the other hand the M3 with a turbo option and 2 bulb options is probably one of the most versitile lights there is. However for pure light output in a small long reaching beam the ultrastinger wins.
Todd