I've been running BIAB with Parallel Desktop as well as VMWare Fusion for many years - works like a charm. Running a DAW (like RealBand), it's a different story. The sound card is accessed via a Parallels or VMWare emulation layer. That means no ASIO driver, and a somewhat slow and unreliable functionality. If you need RealBand, then Bootcamp is a better option. But since you are on a Mac, you could use GarageBand instead of RealBand.

/Björn