I have the KN6000 and after listening to all the bad mouthing about the KN7000 and the sd card system I marched right down town and bought the Yamaha PSR9000. I fought if for about 6 months and when everyone seemed to realize that the problems with the KN7 was them and not the machine, I agreed and went back to town and bought the KN7.
I think I have played the PSR9000 maybe twice since the KN7 came into the studio.
IT WAS DUMB TO BUY IT! I admit it. It is also interesting that the PSR9000 has depreciated almost 60 % in the year I have had it. the KN6 is two plus years old and has depreciated only 1/3 = 33% in over two years. Does this tell you something else.
Tim if you need or want to sell the Kn7 there is a strong market available to you. If you want or need to sell the Yam, oh darn, the used marked it pretty thin and the depreciation is AWESOME!
GET OVER IT!
Learn to love it. You will even know how to properly use it in only a few months and it will do things you never believed. Your Yam will end up sitting and depreciating just like mine
Best to you
Bebop