BB -> RB -> Reaper smile
I just made a Tip for this:
http://www.pgmusic.com/forums/ubbthreads.php?ubb=showflat&Number=446843#Post446843

As for other features in RB, you've already noticed the biggest reasons to use it in your workflow.
A couple more may be the other included extras; sForzando, Sampletank, MIDI editing (with data filters), .. multiple synths/ports .. audio editing before going to Reaper (to save time) .. more mixer/routing options than BB .. lots of reasons to incorporate it as another tool in your toolpouch.

Edit:
I've had BiaB for much longer than 3 years and I am still learning with it also.

For projects, I find that I make progress faster when I move to RB sooner.
I get the basic idea down in BiaB, then right away move to RB to refine the idea .. then off to your DAW of choice to finish up.


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