I haven't really got into Jamstix and only have the free version.
Was looking for a quick way to create a drum track for a song from the Biab chord sheet.

You can get your Biab chords/part marker into Reaper/ReaTrak using the Biab Plugin,
click "Biab Plugin Chords".
You can create up some some ReaTrak Midi Drum Styles from the Jamstix Midi drum phrases.
Just drag the midi sections into Reaper,
create a region with the associated color for that section,
have pre & post fills,
you can add the brown region for solos/riffs ("Redo Drum Riff" will give a different solo each time),
save the midi with "Drums" in name in a folder
Drums, Blues Shuffle 01 Sw8 4-4 80bpm
and in that folder
"Export/Renumber Regions"
Drums, Blues Shuffle 01 + Riffs Sw8 4-4 80bpm.csv
and save the midi track
Drums, Blues Shuffle 01 + Riffs Sw8 4-4 80bpm.mid

In your Biab song imported via "Biab Plugin Chords", select all regions or just a section,
Choose Instrument
Drums, Blues Shuffle 01 + Riffs Sw8 4-4 80bpm.mid
ReaTrak Selection
Set Jamstix to MIDI PLAYBACK
Import Midi track into Biab.
If Biab had Midi UserTracks you could do it all in that.

Biab Track Injector for Reaper
Free Biab Chord Picker Tool