Thanks guys. I saw a post from someone selling SF replacement bodies in which he stated these switches could not stand up to 2x18650 batteries. That didn't sound right so I thought I would ask. Even though Surefire's warranty service is great, I didn't want to have to take advantage of it.
I think you might have misunderstood a post somewhere, or someone else did...
There is an issue that needs to be considered when running high current lamps with the new LiMn chemistry li-ion cells, as they can deliver higher burst currents, and more and more powerful bulbs are becoming available in the after-market for use with these cells. The Z59 is not very good at handling these loads.
LEDs do not have the issue of "inrush" current. A cold bulb has a much lower resistance than a hot one, so when it is first turned on, a rush of current flows that is anywhere from 2-4X as high as the normal operating current of the bulb once heated. This inrush current on incan setups, combined with cells that can handily dish it out, can destroy some clicky switches.