Keep in mind, it's using the SD810 which uses much less power. Waterproof could be a deal breaker for some..
Yeah, but the bulk of the battery drain continues to be the display. The efficiency of the processor MIGHT yield an additional 5% of battery life.
I think the main benefit of the more efficient processors is to enable "always on" google now listening.
Biggest difference I've noticed in the better processors is faster browsing time, and some of that is improving radios, as well.