Dan - you wrote:

With the PSr9000 or 9000pro I beleive that you can not play songs off the hard drive or play songs back to back

That's not so! The playback is a snap off the hard drive. Direct recording is also a ONE step event. Back to back song playback is very easy and glitchless. The overall O/S of the Yamaha has it ALL over the Ketron design. You can't even call up isolated drum patterns on an X1 without sending volume and program changes to the bass and other sounds.
I tried for months to overcome the shortcomings of the X1 as a "live" (arrangerless) keyboard, and couldn't do it. I think, at the very LEAST - all arrangers should function as a simple piano/bass/drum synth first. That's where this all started. The auto stuff is icing on the cake, and ego boosters for beginning and amature players.
The 9k has the most versitility of all of them - too bad the harminzer and I can't play nice together!
I'm sure your beloved SD1 is terrific, but after owning ALL of them, I'd never go back to the Ketron O/S.
I could live with the Kn stuff, but I'm spoiled by Yamaha at the monent.