Honestly, my experiences with pdf viewers on the 770 has been pretty mixed. Evince has a much better interface, but on large documents it freezes up for time to time. Sometimes it seems like the built-in pdf viewer, with its one-page-at-a-time approach, works better for some documents, esp books. Haven't tried this feature of Xournal, but I definitely will!

(A lot of the pdfs I deal with are scans of journal articles, which explains some of my problems.)