I have been wondering much along the same lines myself, since I just spent 16-odd hours on a reading binge using Stanza on my iPod Touch and wondering (for a week or so) if I should buy an ebook reader like the PRS-700 or the earlier (and some say better) model 500 - and even then solely because I want to make sure my eyesight lasts me a very long time still, for I am beginning to think that single-purpose ebook reader hardware is fast going the way of the dodo.