Jon is right.
BIAB is indispensable as a practice tool. There are sooooo many things you can do with it....
For example:
1) Set up 'standard' chord progressions (eg ii-V-I, ii-VI-V-I, I-V-5 etc etc) and play along in different styles. Also a good ear training exercise for hearing chord progressions and quickly classifying them.
2) Working on your time - set up a new style with snare drum set to hit on beats 2 and 4 only - set the tempo to the tempo of a groove you know and just play along for 5 mins.
3) Set up a diff style with snare drum on beat 2 or beat 4 only, and play along...
4) Set up a new style that clicks like a metronome but has beats taht randomly drop out. Make variations of this style with beats that drop out more frequently. Goal is to keep the time solid and consistent even when the beats drop.
In terms of outputting BIAB, I do similar to Jon. Either I output direct to my Tascam Bass Trainer, plug the bass in and playalong with headphones.
Or i sent the BIAB to a midi sound module which goes to a 4 track mixer (with bass in as well) and then routed to either headphones or PA.
Cheers
Paul