I've had mine a week now (from
http://www.texastacticalsupply.com aka TTS) and so can only comment briefly.
I was shocked that the first full charge only lasted a few minutes; I mean two or three minutes at the most. The lamp dimmed and went out suddenly during my first real use, watching the dogs in the yard. How sad. But instead of calling TTS or SureFire, I put the battery back in the charger and let the red light change to green after a few hours. That same battery is in the lamp now and seems completely different. I have yet to use the thing for an entire hour, but there seems to be nothing wrong now. Somehow that first charge (yes, I did charge it before ever using it) was the only failure.
My comparison lights are E2, E1, 5D Mag, Scorpion, and 2MM candlepower LSI. Let's ignore the LSI, okay? The 8NX casts a very usable beam, with a decently defined hotspot
at 35 meters. You could use it to locate an animal in a large oak tree at 100 feet with the entire tree illuminated but the 10 foot animal area more brightly lit.
As a field search tool, for a missing child or dog or whatever, this would be more useful than even that big (50 watt?) LSI. The beam is wide enough to illuminate the periphery while the center spot is excellent.
Again, remember what I'm comparing this to. The M3 and it's ilk might be much better, but this 8NX is surely the best that I own.
Or, briefly, "I like it".