Rikki,
the sampled grooves are one of the features that excite me the most about the PA2X Pro (the second one is the option to load your own samples and the third one is the master keyboard ability, that has enabled me for the first time to use my Yamaha Motif ES rack and my Fantom XR as a part of my Registrations or Performances).
So far I have tried to load only a few samples loops, chosen among the most useful and universal ones; they really make a difference. I have never tried to replace with sampled loops all the drum parts of a style, though.
I have never tried the BIAB Real Drums, but this is not a problem since I have a ton of loops CDs.