As usual, I posted some details and opinions elsewhere:
http://sandsoftwaresound.net/yamaha-ck88-unverified-leakage/
http://sandsoftwaresound.net/yamaha-ck-random-bits/
Quick summary, the CKs are for price-sensitive customers who will be happy with entry-level sounds and a quick, intuitive front panel (user interface) without a lot of menu diving. If you own an MODX, then you already have all the samples and tools. Just learn your instrument! :)
When Yamaha released the Reface series (September 2015), quite a few punters asked for a full-size keyboard combining the Reface synthesis engines. The CK combines Reface YC and Reface CP giving it full-size keybeds. Took almost eight years to respond. [Guess when Yamaha will implement all of your Genos dreams! ::) ]
All the best -- pj
1. It looks like it can split the keyboard, but can it also layer sounds within each split, or at least within the right-most split?
A/BC Part A on the left section and Part B and C on the right section of the keyboard
AB/C Part A and B on the left section and Part C on the right section of the keyboard
A/B/C Part A on the left section, Part B on the center section, and Part C on the right section of the keyboard
ABC Voices on Part A, B, and C are layered
2. Are those live set buttons the same as registrations? For example, can they store different split points, different effects selections, and different parameters for the synth settings and organ drawbars? And if so, are there multiple banks of those live sets?
3. Does it have any kind of background drum/rhythm section? I don't care about automatic chords -- just drums. And if so, can these drum patterns be set, or "frozen", so that they do not change when you select a new live set, assuming that the lives sets are like registrations?