off topic..sorry....There was a competitor out there of BIAB software, called "Jammer Pro"...Not sure if they are still out there?...But I found it more rock and blues oriented, when I played with it, way back in time, and was only midi based when I played with it.....Not saying it does the real band mp3 sound libraries, like BIAB does now, as I have not looked into it since early 1990's, I have no clue what Jammer Pro does now.....But it does generate a band for backing tracks.
Found this link:
http://www.soundtrek.com/catalog/product_info.php?cPath=6&products_id=17 Site is under construction...
So there are alternatives that move into other styles other than Jazz, and Country...and Computer generated music.
Just thought I'd put that out.
Regards.