For WK10, SK-series, I would suggest the following:

1) 8 analog outputs instead of 4, totally and completely assignable to any track in stereo or mono mode.

2) Digital output: with 16 channels

3) Tracks are converted in the keyboard to Wave files

4) Firewire adapter/parrallel or serial adapter. Not every computer is scsi.

5) physical modeling capability

6) MIDI TIME CODE support for synchronization

What else?