I don't have experience of more recent E-paper displays but I regularly use a Kindle Paperwhite that's a few years old. It's absolulely great, but the screen refresh when you turn a page is really slow. That's fine for the use case of being an ebook reader, not so fine for a computer though - typing, for example, would be intolerable. If that could be fixed/improved enough then, I agree, E-paper displays could be great because they're incredibly clear, and very easy on the eyes.
Screen update latency can be optimized for the interactive use case. The default for e-readers is to do lots of full refreshes (slow) because they're less distracting than leaving small artifacts on the page after a partial update.
Yeah, that would make sense: if you can just update the parts of the screen that have changed it should be a lot quicker. Again, for an eReader, when you turn the page it makes sense to do a full screen update: not necessary in other cases. I do really love the idea of an ePaper screen for a laptop. It would be great on the eyes, and more energy efficient.
