Yeah I get great battery life on mine, and since 4.2.2 its improved more so. Before on a mid usage day I'd end the day with around 50% battery left, since 4.2.2 and no other changes to my usage its up at nearly 65-70%....
If I enable Googe Now I lose about 10-15% more battery on either scenario (4.1.2 & 4.2.2) as it sends out my location and stuff to Google during the day, but to be honest I haven't found any real use for Google Now and I don't need t telling me the weather as Sense Weather is there anyway.
As long as whatever device I get in the future has similar battery life I'm content. I just need whatever device I'm using to last the course of a day, and the One (and the S4 before it) both have done comfortably.
But remember no LTE here folks

heck decent 3G can be patchy enough

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Enjoy
Out of interest why did you get a tampered message anyway? Did you unlock bootloader through HTCDev or via a different toolkit?
I unlocked via HTC Dev, then used Revone to gain S-Off but at no stage have I got a tampered message. Just wondering what causes it...