Certainly, for practicing, I decided many years back that BIAB was far superior to Jamey Aebersold or other Play-Alongs. Moreover, that was before the advent of RealTracks! Key, tempo, number of choruses and jazz style were four key factors in this decision. However, I do not think a recording project using either medium is going to give you the necessary spontaneity and interplay from the rhythm section or other frontline members - the best recording sessions, anyway. For jazz, it is essential that that every member of a band reacts to what the other musicians are playing. Recordings and computer programs just lack the emotional response you need for a proper jazz performance, either live or in the recording studio.

Best you get some real musicians to play with you. However, if the project is just to prove that you can improvise, then BIAB is suitable. I do not think it is a steep learning curve to create backing tracks. In fact, our local music shop recently had some courses on how to do this with BIAB and they only went for an hour and a half. Not that even we long-time users have it all down and some of the subtleties do take a little longer to master.

Grah Jive Talk
"Don't worry baby, they'll swing their arses off."