After a week or so of testing, it is fairly obvious that the prs-505 was not built with large book libraries in mind. I bought a 8 Gb memory stick shortly after I bought the reader, and initially I felt cheated: 1500 books fill only a small part of the stick (and cause a long wait on disconnect) - if I wanted to carry around a library (and call me weird, but I do), I would be waiting forever after every disconnect. Then I found the excellent
comic-to-lrf script and I suddenly found a use for the remaining 7.4 Gb

.
Anyway, since I recently downloaded half of Gutenberg (torrent info
here) I tried loading lots of books and checking the response times.
At 1500 books, the reader took 15 (!) minutes after disconnect to rebuild its internal database or whatever the hell it does. Once it is done, it behaves pretty much as normal. But still: large libraries cause a long wait on the Sony.
QUESTION 1: How long does it take for your reader to get to the state where you can start reading after a disconnect (also, with what number of books?) Does a minute added per 100 books seem like a reasonable estimate?
QUESTION 2: Is it me or does the reader sometimes "flake out" with large collections, so that not all newly loaded books are shown in the reader interface? When it does this, if I open the last book it managed to load, it reads "page NaN" in the 'end' section (that lets you jump to the last page). Opening that book will crash your reader, others work fine. For me this seems to start at 1400+ books.
One way to solve the issue , if the Sony looks at file extensions to determine content type, would be a hack that can rename books one the fly from the settings page would work. That way, you could load your memory stick full of books (with an "unreadable" file extension) and then just "toggle" books you want to show up from the settings page.
QUESTION 3: Is there already a hack like this or another way to manage a large amount of books (without using a host computer)?