Hey Alex, good points.
As I am learning more about what is available sample-wise, I agree it is premature to get rid of the hard disk. I am currently salivating over some of the Spectrasonics offerings, including the upcoming Vocal Planet. There is no way those 8 hours of samples would fit in affordable flash.
My favority controller is polyphonic aftertouch. There is no other controller that matches its expressiveness. The only arrangers to generate it were the General Music S2 and S3, to my knowledge. I am using a Roland A50 controller, which transmits Polyphonic aftertouch and a Roland 5080 module which responds to it. With the arranger, currently a Yamaha PSR8000, I need a minimum of three pieces of gear.
Even with fingers on keys you can use foot pedals and even ribbon controllers (ala Kurzweil K2500/K2600. I still think sliders are nice, e.g., to set mixer levels.
Returning to Spectrasonics, they are incorporating a feature called "Groove Control" with their sample disks. I am not sure how this works, but I bet it would integrate well with the custom style facilities on arranger keyboards. Has anyone looked into this?
Clif