Really Well, I've got the Xk, so I suppose I'm not missing much I figured the Systemizer did more.

The Xk has an interesting VOICE LIMIT parameter, but doesn't appear to do too much else besides splits and layers aside from the usual controller assignments. It's also got some kind of CHORD mode that I have forgotten how to use.

Anyone have a PDF of the Xk owner's manual I've managed to figure just about everything else out, but perhaps my CHORD button is just broken.

The Xk arpeggiator has an external clock input, which I have been able to sync to the Miduino.

Anyone else use an Xk -pc

The Systemizer was basically the processing engine from the XK keyboard
controller, with a few additional nifty things like some cool patch chaining
and an alternate patch mode. It was quite cool, and I used to have two --
sold one and the other one got stolen.