I have only a single MIDI connection between the 8-lb Ketron SD90 module and the 26-lb Casio Privia PX560 88-key stage piano. Since I do not care about the local sounds of the Casio PX560, this setup works fine for me with all sounds coming from the Ketron SD90 module.

I also tested the Ketron SD90 with the very compact 11.5-lb M-Audio Code61 61-key MIDI controller - a fairly light weight and compact full size key arranger solution. The Korg microkey 61-key controller is far smaller and lighter than the Code61, but I do not like playing with mini keys, or adding a Kenton MIDI USB Host mk2 to provide a 5-pin MIDI connection.

Thanks,
Paul