One bass feature I've been hoping for -- although apparently I'm alone in this -- is the ability to select bass notes from B0 to G4 with the chords. E.g.:
Amaj7/A1 /B1 /C#2 /E2
Amaj7/A2 /G#2 /F#2 /E2
I think it would help with intonation on a fretless fingerboard to be able to build playalongs with specific bass notes like this.