Hi John.
When the Expansion boards came out if I remember right they were around £200 each.
So not very many people could afford them.
I had some in my first KN7 but when I changed to Tyros I let them go together with the keyboard in part ex. Now I am back with the KN7 I wish I had have kept them but like Frank says you can get some very good voices by tweeking the one you have.

peter b