There's been some conversation about the YC73/88 vs. the CP73/88, so I thought I'd post a version here of something I'd posted elsewhere, going into some more detail about specific differences.

For its extra cost, the YC gives you more than just the organ. There's also more "other" sounds, and related, the FM engine (which is used for the transistor organ sounds but also a whole bunch of other sounds, including FM basses, synth leads, bell sounds, harmonica, brass, strings, guitar, and of course, EPs). YC also has a lot more options in terms of effects and amp emulations, and it can do mono lead line synths with portamento. It also adds the ability to play one of its sound internally while playing another externally (which is always nice, but makes more sense on that model, since one of the biggest needs for this is for playing piano on one action and organ and maybe mono/lead synth lines on another, and the YC is the model that has the stronger organ and mono/lead synth functions).

But the CP still has a bunch of advantages over the YC. It has more piano sounds; the ability to split/layer 3 non-organ sounds instead of 2 (on the YC, a third split/layered sound must be organ); the ability to save customized EQ for each Live Set; and its interface is more direct, which I think can be especially significant since direct interface is so much of the appeal of these boards in the first place. For example...

... On the YC, all your non-organ sounds are selectable from 4 categories: piano, EP, synth, and other, which leads to a lot of scrolling. The CP gives you direct access instead to 11 non-organ categories (Grand, Upright, CP, Layered pianos, Rhodes, Wurlis, Clavs, DX eps, pad/strings, chromatic perc, others), which means there's a lot less scrolling to get to the sound you want. The YC does have shortcuts to jump to sub-categories within its major categories, but it's not as obvious/intuitive or as quick as the front panel knobs. (This also gives the CP the cool "hidden feature" I just posted about, in the thread titled "Cool "hidden" feature in CP73/CP88 front panel Voice selection.")

... On the CP, you can glance at the panel and see/access every setting simultaneously. On the YC, you can't see everything at once... you activate the A section to get to the A settings, then you can switch to the B section to get to the B settings.

... On the CP, you see the name of each effect that you can choose from, and can see "where you are" relative to "where you want to be"; on the YC you scroll through some vague number of cryptic 2-character abbreviations.

... The CP has Attack and Release knobs, the YC has a single EG/Filter knob, which provides more options, but whose use is not so intuitive.

All of those largely come down to the fact that, to fit all the organ and other new controls on the YC, the piano+other controls had to be ganged up and consolidated. Meaning that the CP is a bit more immediate and simple in its operation, while the YC is deeper, but not as immediately clear. I think ease of use really favors the CP, especially when it comes to selecting/combining/manipulating sounds live during performance, if that's your thing.

I don't know if I've covered every YC/CP difference here, I may have missed some. But I think it's worth noting that a YC is not a "CP and more" as some people may be seeing it -- there are some valuable things you give up, too. Based on my own priorities, the CP would actually be the preferable board... but that depends on your needs, and also what else you may have available to pair it with.