I'll get higher res files up tomorrow
If you have the right tools to edit PDFs with you might be able to do something with the margins - Creative Suite has whatever Acrobat Writer is called these days in it?
If PDFs like that were the only sort of thing, or the majority of what I was going to read on it, I think I'd seriously consider paying the extra and getting the iliad. However, if cost was an issue, and I was going to read other stuff as well, then I might go with the 505. The larger screen does have an advantage for this sort of thing though.
Two caveats: I used to read technical documents on my N800, which was far from ideal. And I'm a bit long sighted and as a result find smaller text easier to read than larger text.