Can't see Yamaha making a module, as Roland's BK-7M is doing pretty bad sales wise...the store I visited on my last tour in Newfoundland had three BK-7M modules returned by dissatisfied buyers. It is hardly a success story, although some of the accordion crowd seem to like it.

My guess is some kind of a package that allows the instrument to be set up as a dual manual...maybe a special controller keyboard that is designed to fit under the Tyros4 (and perhaps T3).

I will say that anyone who actually knows, isn't going to say anything.

Ian