I actually started e-reading on a 3lb netbook, and still found it preferable to paper books, to the point that reading was my primary use for the Windows computer I carried around with me
During the several months that I did not have an e-reading device, I found myself reading much less just due to the lost convenience of obtaining books, carrying them around, keeping my place, reading in bed (w/ LCD backlight) and turning pages.
Pretty much the only advantage of p-books over e-books in terms of the actual reading experience is familiarity, which is quite quickly overcome.