The Lux III and Lux I have similar battery consumption curves, since they're effectively the same part. You're not going to get extra throw out of it - but you will get better tint control, and if you adjust the Vf of the head by picking a specific LED, that'll modify the battery life somewhat up or down. You're NOT going to automatically get better throw - better brightness with a higher binned LuxIII, maybe, but not better throw, which depends mostly on the reflector in the KL1 head. The terms '3W' and '1W' are misleading with regards to the Luxeons, for the most part.
You'd probably be better off getting Chop or someone to replace the innards (circuits, LED, and reflector) if you want to improve the throw of the light. The reflector affects the throw and the spill, the brightness (a good T or U-binned LuxIII) affects the intensity of the light, and a more efficient circuit could help with battery life and maybe brightness.
At this point, you've effectively kept the shell of the KL1 and replaced it with all new insides. One option, since you do have an E1e body, is to get an Aleph 1 for a similar spill pattern with slightly better throw and an LE to go with it. /ubbthreads/images/graemlins/grin.gif