I did not switch to the Luci to save weight and not sure it really is a weight savings. I just like the quality of light better. I am usually solo but i have always been annoyed by others wearing headlamps that obnoxiously shine right into my face at night.
Yep, I really don't like the headlamps in camp. Diffuse light is much better. It was minor weight savings for me, but a better light for my use.
Then I guess I don't understand your aversion to batteries with respect to a headlamp or water treatment.
Not a distinct aversion, so much as if I bring a headlamp, I feel compelled to bring extra batteries in case it turns on inside my pack, if I bring the steripen I need to bring extra batteries too. Without weight penalty, both these changes made my loadout simpler, and less "stuff". I'm not a luddite, I just want simple/easy/friction free. (I LOVE the jetboil, despite non-trivial weight, for exactly that reason)