Band in a Box to an arranger, is like a Workstation to an arranger, in that there are many overlaps, but they are designed for different jobs.

Band in a Box:
Great for projects, waste of time for on the fly backing.

Workstation:
Great for voice manipulation and real time control, waste of time for making and using styles.

Arranger:
Great easy play features and backing for OMB waste of time for any serious project work due their inflexibility.

Programmable real time control and easy operation of advanced editing is a must for project work, as is a highly flexible (And predictable) backing track creator. (A limited NTT (As in an arranger) is of no use whatsoever)

Bill