[blindluke]

That's just a single data point, but here's my experience. I have severe myopia, and I experience discomfort when reading from a screen over a prolonged period of time. I read a lot, and I can't read for more than two hours even on a quality LCD screen. With e-paper, three hours of continuous reading are not an issue. If my reading habits were as simple as reading for an hour before bedtime, I don't think I would need anything more than a tablet.