I probably won't be keeping that many books on the device at a time - I don't imagine many situations that I would need a choice of 600....
The main reason for me wanting this is that a bout 18 months ago the wife made me get rid of most of my books as we had no storage space for them. The room that housed them was being turned into a bedroom for our eldest daughter (who was moving rooms to make way for her new sister).
Even now when I buy a new book, I see the look she gives me thinking about the space. It makes me feel guilty as I am almost at a 1 in 1 out scenario. With the reader it is a win win situation (although there will be a few key books I will still buy the hardback of).
Again, thank you for your help. I am trying to read as much as I can - currently lurking through the current posts