Hi George
There is a Piano made with an 88 note hammer action keyboard that has full arranger functions, unfortunately they have not yet released a portable version, and it is also quite expensive.
The instrument is the Wersi Giga Piano; (And it has all the arranger functions of their OAS keyboards) it also has advantages over the other Wersi OAS instruments, in that the piano samples are taken directly from The Grand VST by Steinberg. (Other OAS uses have to purchase The Grand VST separately)
Just thought I would bring it to your attention.

Bill