Earlier quoted context omitted.
Use a Mac with a Retina display for a week and see whether you don't notice a difference — and it's certainly nowhere near half the battery life. Everyone I know who's done this has never wanted to go back.
As someone who went from a mac (for the last 15 years including several retina MBPs) to a 1920x1080 13" screen on a lemur pro, I really don't find that it makes a huge difference to me. I thought it would really irritate me but it doesn't.
It's kind of like going from 144Hz back to 60Hz when playing FPS games.