I cannot for the life of me understand why someone would consider the SD7 over the SD9. Have no idea about the difference in price though - maybe you consider taking over DonM's unit and that might clarify things.
The SD9 has enough features to keep someone with just a little creativity busy for a very long time. My Audya is eight years old, yet to this day I still tamper almost daily with new styles for it, despite the lack of tools to do so.
Yamaha is awesome and much more exciting (to me at least), but I have to admit that somehow the sounds of the various instruments coming out of any Ketron unit are just much more seperated and clear than anything else - I do not know how they accomplish this. For easy, first take amazing recordings, they are hard to beat.
DNJ, I can see that your mind is made up and I can understand why. Now take some good advice - go for the SD9 instead. It might cost you more right now, but you will be glad you did in the end. Plus it will save you the funds for a new Genos in the long run as you will have more than enough to keep yourself occupied.
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Make sure you'll fly forever!