Access masks are rock solid - if people are reading your private forums you've set the permissions up wrong. I also a gree about password protected forums, I think its a waste of time and a nightmare to maintain.
I do hope the admin control panel is overhauled for vB 3 - as its starting to get a bit strained. Needs to be more user friendly, with more "quick" options for dealing with many users, forums, or groups
I'm looking forward to it though!