I've just upgraded my prs-505 to firmware 1.1.00.18040 and I really don't like the results, specially regarding the rendering of PDF files. I read a lot of PDFs that come with many illustrations and multicolumn layout, and if I want to be able to see the illustrations I must use the "small" level of enlargment, in which case the text is minuscule, or then use the "medium" or "large" enlargments in which case many illustrations are completely scrambled or not shown at all.
Firmware 1.1.00.18040 comes with the ability to read the epub format and that's attractive but I think I'm willing to sacrifice that if it means getting the former PDF renderer, which was not perfect but at least more usable than the current one.
I suspect that getting a downgrade is going to be very hard
so I would also be interested in hearing about alternative solutions such as hacking the reader in order to use other pdf renderers or converting the PDF files.
Thanks a lot!