I see your dilemma, two tactical UIs with XP-G2s, one with more throw, would be a little redundant. My combo - the floody LV XML Pro UI paired with the LV XPG Turbo (both shown in my first pix above) makes more sense.
Also the 14500/Li-ion step might not make sense if you don't plan on a reasonable investment in flashlights. Keep in mind our light perception is roughly subject to the square/square root laws where you need 4x the lumens to appear twice as bright. Said another way, while a 14500 will double the lumens over a AA, it will only appear about 40% brighter.... (This is one of the reasons I'm a low lumen enthusiast - for about half the perceived brightness, I can get 4x the runtime).
Maybe just get a Burst Mode XML Pro 2L (since you're looking for power) and run CR123s? Then consider 17670s and 14500s (which can Lego to either) down the road?
I can see your point about low lumens - the human eye is a wonderful thing as is, why make it 'stop down' with loads of lumens. Compared to a borrowed Fenix head torch putting out around 205 lumens it still holds its own given what I payed for it; 34GBP IIRC.
It's a case of I say 'yes', my wallet (and my sensible side) says 'no'!
Thanks for all the help reppans, I really apreciate it.
All the best
Jacob