I second Mario's idea of separate initial screen choices for separate workflows.
Photoshop does this with the options for Essentials,Design,and Painting as the beginning screen options.
Cleans up the workspace to begin with.

Then you have the ability to add more windows/palettes if you want.
These can be free floating or docked to a menu bar at the top.

I think being able to customize your workspace is an important feature to be sure.
That way you know where all your tools are without having to hunt through a multitude of drop down menus which can be very frustrating especially for a newbie.

Also have the ability to return to "Classic" view for those who desire it.

How about a Realband button that would automatically open your present BIAB work in Realband without dropping and dragging.
Always felt a seamless merging of the two programs would be the way to go.
Maybe under a new name?

Carkins