IMO, the only reason we have only one reader with e-ink is because the Sony reader will not access web pages directly. Me and my wife do most of our reading on the computers, because it is news and commentary we most consume. When we can do our Internet reading on an e-ink screen, our computers will be used primarily as computing devices, not web browsers.
We prefer e-ink screens because they can be read outside. We like to sit outside, so she would rather read paper; books and magazines, and I would rather do audiobooks. With an e-ink device that employs wifi, we could spend more time outside.
E-ink is far superior to LCD as far as readability goes. When the refresh rate for E-ink improves, people will use it primarily for most of their reading.