Hi Phestus,
First off, I'm not employed by PG Music and the information that I'm passing on is purely from recollection. Ultimately, you will need to contact PG Music to get the correct information. (I'm a BIAB user.)
Since version 2011, there have been a couple of modifications regarding the way in which BIAB handles Realtracks and Realdrums. Because of this, I suspect that it's necessary to get (as a minimum), the upgrade that will enhance 2011 and modify it so that it will work with any of the newer Realtracks. This upgrade is listed as $69 and doesn't include any Realtracks or Realdrums.
Prices for the different packages are here ...
http://www.pgmusic.com/bbwin.packages.htmIt's also possible for you to buy (say) the UltraPlusPak which will include the above upgrade and also all Realtracks and Realdrums for $159 (currently on special).
According to the below webpage ...
http://www.pgmusic.com/realtracks.all.php?os=winBIAB 2011 had Realtrack sets up to Set 175. With 2015, we're now up to Set 227. If you scroll through the sets listed at the above site, you'll be able to see and hear what has been added since Set 175.
Hope this helps,
Noel