RC - I have been using BIAB since the 80's... it is an amazing program! Yes, you can load midi files into BIAB and see the individual parts on manuscript and print them if you desire. Easily transpose from original to any key.

The MIDI portion relies on your keyboard or sound module to create the backing tracks - or you can use a PC-based virtual synth that is included with BIAB to create the audio. A good while back they implemented "Real Tracks" which are recordings of studio players comping (or soloing) over chord changes. The "Real Tracks" are organized by style and BIAB assembles the chord audio snippets into the changes you enter (based on style) and creates the backing for you. Works the same way when generating backings via MIDI - just without any studio audio.

The prices do vary based on the content of the package you buy. The most expensive version of BIAB (Audiofile version I believe it is called) includes all WAV recordings for the hundreds and hundreds of "Real Tracks". The lower priced versions employ MP3 versions of the audio recordings.

BIAB is an amazing tool which is probably a mandatory tool for all the jazz students at Berklee and North Texas jazz programs. Sure makes it fun and easy to work up any tune and enjoy the fruits of your labor.

Hope that helps...there are many tutorials available and PG Music has a great forum where they answer questions on the features included.

PS - if you use the PA4X, it is not hard using BIAB to generate a complimentary set of accompaniment tracks - just enter the exact tempo you use on PA4X, select the BIAB style that would most closely match the PA4X style, enter the chords you will be using on PA4X, and generate the backing...you can then save off the individual tracks from BIAB and use just one or more to augment the PA4X backings....

Have fun!