Thanks all for your input.
Penforhire: I was thinking that the touch film over top of the screen on the older models may make them more susceptible to scratches than the new models (or less, depending on the nature of the film). But, from what I've read so far, there does not seem to have been a big difference. And yes, I think you are probably right, luck will play a big part in how the device fares after a drop.
Adityadubey: I don't mind a bit of character, I just don't want all that messy e-ink leaking out into my bag.
I suppose this is another distinction between ebooks and pbooks. If you drop a pbook and bend the cover you have damaged one book, but it wont stop you finishing it. If you do the same to your reader you may have curbed your reading until you can afford a replacement.