Not to confuse the matter too much, but I bought the MegaPAK (the minimum level that had ALL styles), and have been quite happy with the results, even though it had a limited set of RealDrums/RealTracks.

Here's why it worked for me: After some initial experimentation, I never used the RealDrums/RealTracks at all. I now use MIDI tracks only, and just route the output through some high quality virtual instruments and it sounds fantastic. Also, I feel like I have much better control over the MIDI than I do the "Real" instruments.

critter, if you're on a budget and you're okay with tweaking/routing MIDI channels, you might consider an upgrade to the MegaPAK coupled with a good, yet inexpensive soft-sampler -w- library, such as Vir2's "Vi.One", which is only $99 at Musician's Friend/Guitar Center.

But this is just my way of working. The "Real" instruments in BiaB certainly give some bang for the buck in terms of rapidly getting something going that sounds pro, out of the box, and the UltraPlusPAK for a $299 upgrade price, shipped ready to rock on a USB drive, is a pretty good deal.