BTW, there is work going on that is converging on the aboves situation. MAS has some of the above, but you can't use your own samples, and you can't run it as a dxi in SONAR.

Programs like Band-In-A-Box have similar AI, but not applied to live performance. You can play Edirol's software with an arranger like the PA80 within SONAR, but you have to use their samples; and the PA80's are better, in my opinion (but it is fun to experiement).

But I bet in another 5 years, it will come together.