At risk of sounding like a stuck record, if you're going to try beta 1 start a new profile or back up your existing one. Instructions here.
Seems there's a bug with big bookmarks files not being imported properly in beta 1:
http://forums.mozillazine.org/viewtopic.php?t=605038
If you have issues, it might be worth trying a nightly, but you can't take a profile that's run a recent trunk nightly back to beta 1, or your bookmarks toolbar folder will disappear (due to #387746 [Firefox
laces]-New left pane for Places Organizer [All]).
Seems there's a bug with big bookmarks files not being imported properly in beta 1:
http://forums.mozillazine.org/viewtopic.php?t=605038
If you have issues, it might be worth trying a nightly, but you can't take a profile that's run a recent trunk nightly back to beta 1, or your bookmarks toolbar folder will disappear (due to #387746 [Firefox
laces]-New left pane for Places Organizer [All]).