If you want to integrate to Reaper look at ReaTrak.
The thing with the Biab Plugin you can leave the tracks in that (local folders) until all is good.
You can have a Biab Plugin on each Reaper track generating multiriffs for as many instruments as you like midi or real.
You can send midi to any track and virtual instrument, send Direct Input RealTracks to the host through Guitar Rig or Amplitube by adding the Guitar FX VST after the Biab Plugin.
You can redo any section of track with the MultiRiffs and just slip it in.
You can have a Plugin on one track with a lot of different drums in to see what one fits best.
These can be all played back in sync with any tracks if already in Reaper.
You simply select the track in each Plugin you want played back in sync together.
When you have got it how you like just drag those tracks from the Plugins into Reaper.
ReaTrak will also generate RealDrums directly in Reaper giving you more control, allowing editing of any section and giving individual volume control of the sections, choose the shots n holds you want, adjust pushes.