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?