Is Surefire KL5 Lux ok to use with 2 and 3 123A's lithiums ?

[lightinsky]

I know a while back there was some confusion as to wether or not the Gen 3 Lux KL5 Led head could be used with 2 and 3 123A's lithiums. I currently run it on my OD G2 but wanted to know if I run it on my 9P's body with 3 batts if it will affect the led or take the light out of regulation. I mean what is the benefit of using the KL5 with 2 vs 3 or vice versa ? Any help would be appreciated.