Those playbars are OK for linear files, but I would never, never use them for non-linear courses. The Next button on the playbar will always go to the physical next slides, the user can drag the progress bar (not sure you have one in the playbar that you use) to mess up all your nice branching plans. And in CP6 creating custom navigation has become much easier than before if you use shape buttons either on master slides or - for more control - timed for the rest of the project. I'm sorry if I'm now confusing you even more.
Lilybiri