Why only aim for 4 hours of screen on time? I understand the battery will be smaller too but so is the screen. I'd hope to see a bit more. Also, remember that most people won't care about thickness so much especially if it's rugged enough to not need a case.

But anyway good luck with the project! I backed the first Pebble and I'll probably use Beeper once it's fully available. You have a history of delivering on your promises. I just want to wait a bit to see how this one turns out in detail.