Why doesn't Surefire appear to make a Cree conversion head for the M6 Guardian? With six 123 batteries, you could probably get several hours of 200 lumen output in such a combo.
I realize 18v would fry an unprotected LED, but with the right step down circuits that limit the current to the LED, it could work, right?
That would be one awesome light if the LED conversion head had 3 settings, such as high 200 lumens (with perhaps a few hours runtime), Medium 60 lumens (moderate runtime), and low 15 lumens (with tons of runtime)
I love the SF M4 and M6, but these things eat batteries and yellow well below an hour in my experience. A top of the line Cree conversion head would make it actually practical.