NY,
I can't really disagree that the price of all arrangers are pretty high. I'd even go so far as to say at $3k they have reached my upper limit as far as perceived value by me. After this price bracket then they truly need to do a combo board that has everything on it that a great arranger and a great workstation have. Including what you have mentioned and for me an arppegiator would be a must have. I'm really not sure why an arranger should cost that much more than a workstation.
jam on,
Terry