I just made my first full BD backup on a BD5 => Success! (The original contains 81 x m2ts streams). The BD5 disk was filled to 97%.
Menus, Main Feature, Extras (quick encode), Subtitles, all are working with my SW player (I don't have a standalone yet for doing further tests). Wow!!!
The only bug (?) I suspect is that the 2nd language track is missing, although I selected 2 languages in the Settings/Setup dialogue.