This doesn't answer your question.
Rather I thought that you would find this video of the 902 handling technical pdfs (including standard zooming and a scanned book with 3 columns) illustrative.
Here's the video:
http://www.youtube.com/watch?v=1Aohm...eature=related
The part described above begins at 4:40.
The comments might also be helpful.
Q:is it a difference if the pdf is scanned as an image or traced with ocr so that it is text/searchable? I mean does the layout mess up when it is not an image anymore?
pocketbook:Actually, there is no difference in the handling times (book openning, page select) , but you can not read scanned books (images) in reflow mode.