Surefire KL3 with 4 CR123's?

I asked this question earlier and posted in Flashlight Electronisc, etc, and had it moved to Led forum, but thought that this might be bettter discussed here. I know that KL3 is advertised for 6-9 volt applications, and upper end would be 9.75 volts or so with fresh CR123 cells. I also know that you could void a warranty by using excess voltage to KL3 circuit. But, has anyone tested the KL3 circuit with 4 CR123 cells, looking at longer runtime. If four CR123 cells would work, then possibly three RCR123 cells would work. What are the real upper voltage limits of the KL3 circuit? In this case I am talking about the gen 1 KL3, but this might be applicable to the newer KL3.

Bill