Thanks Pipeline,
I have had a closer look and I agree, this is very convenient to use and even does Session View in Live which is fantastic because I tried recently to emulate this behaviour.
One thing that I find missing, although that me musing it, is the following excellent feature in RealBand.

When I have imported my song into RealBand from BiaB I like to add a further number of RealTrack and Midi tracks based on styles different from the original style from BiaB. I can do this easily in RealBand and, when it is saved as an SEQ, I can go back and regenerate the tracks individually or as a group and RealBand remembers all the styles used.

So, its fiddly compared to having it all in the DAW but much more flexible. I'm assuming the plugin is intended to bypass RealBand completely.