I use unrealBook also (and wrote a lot more about it in the recent topic "My new Digital Music Reader" ...

You can do some (limited) editing in unrealBook: add text, draw lines, circles, erase, etc. I don't do that very often though; I usually edit my "master" file on my computer, then email it to myself and add to unrealBook from email, or as one person mentioned, by putting new/edited files on DropBox then use unrealBook's DropBox integration to quickly get the file(s) into unrealBook.

There are a lot of music-reader programs out there; I imagine all are decent, just differences in some features, and "in the details". unrealBook happened to work well for me, so I have stuck with it. I use a lot of its features including MIDI (to recall Registrations on my Tyros), set lists, the "keywords" (metadata), searches, etc. etc.

-Jim