Segatang,
Try going to Prime View (
www.pvi.com.tw).
Phosphors tend to be chemically active so E-Ink may have problems with the idea of making the white capsules glow in the dark.
E-Ink's flexible sheet is a replacement for liquid crystal, not the whole display. That's why they need something addressable to build an electric field across. Until something like Plastic Logic's flexible TFT can meet the performance, cost and, reliability of the standard inorganic transistors and conductors on glass, it will be hard to build a business case for switching. For now, enjoy your E-Ink and glass sandwich.
Entirely reflective displays have the same contrast no matter what light level is used. It's just easier for the eye to read if you have enough light. The contrast of black ink on a white sheet of paper is the same in the dark as it is with a light on. So... make sure you have a light on.
About the bistable nematic display, it should be pretty good over a wide angle. White "luminance" will depend on how good the white diffuse reflector is behind the LCD and how much light gets eaten by the various layers between. Black luminance (you want as little as possible) depends on how well the LC absorbs the light and how little reflection there is between the LC and your eye.
NatCh has a good point in that the market for a flexible reader may not be as infinite as press releases seem to imply. We
like writing on and reading off flat surfaces. If we can put up with cell phones, PDAs, e-books, UMPCs, notebooks and so on, what's driving us to a roll-up display? For that matter, where would the rest of the computer go? Check
this old news.
Artist's conception.