That's why I love using RapidComposerVSTi with Biab/RB
it expands the midi capabilities way beyond Biab's.
You can have any midi/phrases where you want them and not just take whatever BB generates where it generates.
So you can save Biab midi/MSTs to a phrase.
As many chords per bar as you like.
Change Signature/Scale anywhere.
Store Virtual Instrument keyswitches within a phrase that will re-fit anywhere to any chord/scale.

I love RealTracks but as Bob, Mario and others state, more versatility with midi.
That's why I'm trying to get PG to make the RealCharts/Tabs usable with Virtual Instruments same as Ample Sound can play Guitar Pro Tab and save measures to Riffs.
So the Articulations in Control 85 that represent Bends, slides, Hammer On, Pull Off (Vibrato could be added) can be converted to custom keyswitches or midi bend info for your Virtual Instruments.
Also Export the TAB in the MXML.
You could have a Sax play a guitar piece as a complement or answer to a guitar.
You can create custom Solos within the DI RealTracks by adding a DI Virtual Instrument to any section of RealTrack.

http://www.pgmusic.com/forums/ubbthreads.php?ubb=showflat&Number=404310

http://www.pgmusic.com/forums/ubbthreads.php?ubb=showflat&Number=406203

Biab Track Injector for Reaper
Free Biab Chord Picker Tool