John thank you for the summation.....having a preference for using only one KB comes from being a gigging KB player for many years...
If you played out for a living which you do not you would see the logic in using a single unit for many transport reasons, setup, speakers, stands, cases, mixers, etc, in & out each job. Plus I can definitely sound just as good using only one KB for sure. After all the KB is just used as backing for my vocals and take the place of a band.That said I admire your persistence in digging in and taming the OS
on the Ketron SD7.
I wish you good luck and good times using it.