I've been doing this for some time also. A few years ago I used two keyboards plus two modules. I had piano on one module, strings or organ on the other, then the top keyboard (a DX7) for lead sounds. All the bottom keyboard did was play styles and control a drum machine. Now you can do all that with one keyboard.
One thing I liked about the Roland G800 when I had it, was the capability to assign plus and minus values to the volume pedal. You could assign one sound to full on, and another to full off. Then you could get any combination of volumes by moving the foot pedal.
Some day we'll have the perfect machine. It's not here yet, but we've come a long way way.
Don