My goal is to integrate my own bass tracks with real tracks. The live interaction of bass with real tracks makes them more "real". With my Motu interface and line out from amp I don't think there is any difference regarding whether recording in Biab or Sonar. Once recorded I can easily audition various real tracks or drums if I stay in Biab.

Another reason I like this is that I spend too much time searching for bass lines that don't fit the groove.

My 2 cents.