Until then, you should be aware of this software:

http://www.midimaestro.com/

Use BIAB, RB, PT to create the "base" songs.

Export to MIDI Maestro for Performance. That is what it was designed to do.

Watched a kid use it as the Pit Band for live Broadway Show type performances, him and his laptop and a few MIDI synths. He was able to match Tempo, Volumes, etc. to the live performers onstage much as a conductor of a live Pit Band would. Impressed.

--Mac