I observe from reading this thread that some people would like the extra brightness of the 350mA version, and others would prefer the longer run time of the 200mA one. However, one of the big advantages of LEDs is that they can be run efficiently over a wide range of power levels.

Is there any chance of a Key-Lux AA with multiple power levels?

My ideal would be continuously variable, so that I could adjust it to the minimum comfortable level for the task at hand (turn the head and it switches on to low; keep turning and it gradually gets brighter?).

Failing that, a few discrete levels, or even just two: full power and a level that is appropriate for close work (hopefully something that will last well over 12 hours)?