The Sonys are too small for me unless I wear reading glasses
When you get to 50 you will know what I mean
The Kindle DX is very nice but is limited by its flat directory structure which prevents a lot of files being stored and retrieved. It would be great with a custom-written file browser, and some support for directories (folders in micro$oft-speak), but it looks like Amazon have tied it down so much that nobody has bothered to get inside it.