I'm not sure Band in a Box still has downloadable demo versions. ( mind you, I could be looking in the wrong place haa haa)
What PG Music appears to be doing nowadays, is offering a 30 day money back guarantee if not satisfied. http://www.pgmusic.com/bbwin.demos.htm
Guessing it might have something to do with the Real Tracks. They seem to be slowly moving more & more towards audio styles. These audio files would be too large to download just for the sake of a demo, & without them, you're missing the full potential of the newer versions of Band in a Box.
They do also have Powertracks sequencer http://www.pgmusic.com/powertracks.audvid.htm
It also has a Lead sheet window.
Hardly use my Powertracks anymore, prefer using Real Band which was part of my Band in a Box upgrade download.