"Generating Music. Please Wait..."

I usually see an "Initializing Accompaniment" message
but either way an hour seems really excessive. That usually lasts a minute or so at most here.

But yes, RB is an ideal tool to replace the BB tracks one by one.
In my workflow, one of the first things I do if I plan to replace all the tracks is use the 'Make all BB tracks regular tracks' option, so it doesn't try to keep generating them (and possibly causing the above mentioned screen).

Then I can work in more of a DAW like setting.

I do not work here, but the benefits are still awesome
Make your sound your own!