I think the Q you have to ask yourself is more of when and where in the creative process you need/use BIAB? When I use BIAB I do it very early in the process and then I need to be moveable and then really the version on my MacBook is the one to go to (although the PC-version of BIAB is superior). All the midi-styles work on both platforms anyway - the realtracks don't.

I use BIAB mainly for LapSteel, Harmonica and Mandolin + some old midistyles that I did in the past. The LapSteel was a huge leap forward for BIAB and I wish they would focus a little bit more on instruments that give a bit of character, insted of yet another strumming-guitar...?

Product owner: BIAB Win 2009 MegaP|Mac 2011
PoCoX8|MD3|H4|VSS3|DVR2|
PT 9.0|Reason 5|K4|Goliath|Ivory|Trilian|VG2|
MacBook 17"|2.8 mhz|4 GB|OSX 10.6.7|One|Bandst.