regarding your initial question:

In my opinion the changes made since 2009.5 have been nothing short of game-changing. (Especially if you like real tracks and the other audio features)

The ability to make high quality songs quickly in BIAB has gotten MUCH better since 2009.5, and the ability of RealBand to continue generating content as the project is fine tuned has also gotten better.

Since 2009.5 the real tracks are much more dynamic, and they also take up less space and sound better

If you go to the video page and look at the videos for every release since 2009.5, I think you'll see a LOT of things that interest you.
http://www.pgmusic.com/bbwin.demos.htm

If you don't, check your pulse.