Just a quick few words on the subject...
Sadly, we have had a few attempts at a convergence of the VSTi/WS/Loop player and arranger, but all have fallen flat on their faces, either half-assed WS sides, or half-assed WS sides, and all priced beyond their capabilities. The MS was SUCH a good idea... sadly left to the hands of a man unwilling to make it work. I have a nasty feeling we won't see it's like again. Dom has apparently seen the light, and abandoned any serious arranger development, choosing to concentrate on it's VSTi/WS side.