I've tested the DX only for a few days, but the scaling of PDFs seems to work nicely (including one scanned book, Bondy &#38; Murty's Graph Theory,  <a href="http://www.ecp6.jussieu.fr/pageperso/bondy/books/gtwa/gtwa.html" rel="nofollow">http://www.ecp6.jussieu.fr/pageperso/bondy/books/gtwa/gtwa.h...</a> )<p>On single column book-page stuff, so far I only came across one figure that looked bad in portrait and had to be seen in landscape. Otherwise fine, if your eyes can handle slightly shrunk type.<p>P.S. by scaling, I mean the fixed scaling the Kindle DX does to fit the PDF on the page. User-controlled font-size change is only available for the mobi/azw format.