One answer that would solve just about every need mentioned would be a Yamaha S90 and a QY100 or even better a QY700. I'm also a Kurzweil fan and have enjoyed used PC88's and PC2's with arrangers on stage.

However, I pulled a muscle in my back last year for the first time while carting around my Kurzweil and took that as a warning - backs don't last forever and it doesn't take much to end your 88-note keyboard moving days for good. The Yamaha 9000 Pro arranger at 45 pounds is still a pretty good 76-note synth-action compromise to heavier 88-note weighted-action keyboards with less features.