Sorry, I lost track of this thread somehow.
At any rate, according to
Surefire's website, the 1,000 lumens E2DLU-T will run for 2.75 hours at high output, while the 500 lumens version, if I remember correctly, was either 2.25 or 2.5 hours at high output. So unless I am misremembering, it seems like at worst, the runtime will be the same, with the more likely best case being that the runtime will be slightly longer with the 1,000 lumens version.
I am still on the fence about this (which probably means I'll buy it soon, since I've been on the fence for 4 months), but so far, aside from my wallet getting lighter, there don't seem to be any downsides to this light...? Plus this will give me an excuse to upgrade to the LFP 123A batteries...
I actually don't know yet. But I doubt the LED is close to twice as efficient. There are many examples of "upgrades" of models with much higher brightness but none or 10-20% more efficient LEDs. So I am sure this is another case of lumen race with higher lumen as a selling argument but with shorter runtime instead.