I have the HK UTL and have not been satisfied. The lamp is not shock mounted and I've found that it the element breaks easily. It costs $22.95 to replace and it's hard to find one sometimes.
I switched to the SureFire 6 volt. The disadvantage to the SureFire is that it is big and ungainly and holsters are hard to find. It is a much better light though.
HTH
Jeff