The KL6 is an interesting setup. While is has a generous head diameter and overall mass compared to other SureFire led lights it actually does not handle heat well. CM and I have discussed this problem and we both have noted extreme drop off in output after being turned on, as much as 20%. What we finally concluded was the best setup for the KL6 head is a Cree, or Seoul emiter. The real advantage being the large reflector inherent in the KL6 design putting out great lux, and less heat generated by the Cree and Seoul emiters due to the lower wattage presented to the emiters, compared to the stock Lux V. I currently am using a Cree P4 emitter, and am looking forward to a good low vf R bin Cree.
My point is that the L6/Kl6 may start out at 100 lumens, or even 120 lumens, but will drop off quickly after startup.
Bill