RC40 comes with very comfortable shoulder strap, so the size is not real problem for me, and don't forget, RC40 can run full brightness without step down, so K60 vs RC40 is not an easy question. Overall, I think, If need a real useful searchlight (more comfortable to use with built-in battery, no step down, similar peak beam intensity but wider beam etc) RC40 would be better choice, but as a flashlight fan, I vote K60 and newer and more and more powerful LEDs.
mark, I'm sorry but I don't have K40M.