The TK10 on turbo is indeed very bright and can be used for extended time. However, runtime is greatly extended on low mode which is still 60 lumens and pretty darn bright. On high, the head will get pretty warm. Im still having real trouble deciding on a favorite. The Fenix is so cool, well built and versatile, but that Surefire 6P LED...well, theres something about it that says "the best". I dont know, its like having multiple SAKs, how can you really choose a favorite?