When I stated backward compatible I meant files from newer Technics keyboards will not play on older Technics keyboards.
Example: You cannot play songs from a KN-7000 on a KN-6000 on down. In fact you cannot play any files from a KN-7000 on ANY keyboard in the World other than a KN-7000 and a KN-2600, unless you go through the tedious task of converting a Technics file to a midi.
Can you explain exactly what you find so difficult about the Yamaha OS? I'm sure someone can help. I agree with you on the videos, I had a KN-3000 and 2 VHS tapes explaining the OS in plain English...learned a lot from those videos that I still have.
Anyway, you are correct, to each his own, and everyone is different, and that's what makes the World go round. The KN-7000 was and still is a great keyboard.
Have a good time in Pakefield