so-leks,
To me, the most natural position to hold a flashlight, gun, knife, etc. is holding it with the arm extended and pointing to the desired direction. Twisty lights and ones with side clicks make the most sense. Lights with side click switch like the new Zebralight SC30, unlike twisty lights, let users access any level of brightness with a minimal number of clicks. This instant access to any mode is the main reason I need a light with a side click switch. I have seen button-celled lights with a side click switch, so I don't think it will be difficult to use on an AAA light.
Flying Turtle,
The clip on the Proton Pro is fantastic. I wish LiteFlux and other companies would use this type of clip. Since I am waiting for a Zebralight AA light and not being a collector, I am not likely to buy the Proton Pro. I think it is a nice light though.
PJD,
I am sticking with AAA and AA lights for now. I am in a green phase with the rechargeable batteries at the moment.