This is a huge disappointment to me, and may push me in the direction of the PX-5S or MOXF. I would not be happy shelling out that amount of cash for something where half the sounds are sub-standard.
SSM
Sounds like you're looking for something that does more the job of a Yamaha S90XS, or MOX(F). As you also mentioned the PX-5S, ideally you can find a music dealer who has that instrument and an MOX keyboard in the same room - to get an A-B comparison.
The CP series instruments are highly piano focused - even with the inclusion of a large block of non-piano sounds. While there is a degree of editability, and the availability of effects, it's just not as extensive as the engine in the Motif. You can't quite get the best of both worlds in one place with Yamaha, yet. The closest thing is likely a loaded-up Motif XF8; but at 62 lbs. it's a lot of keyboard.
There are places in my gigs where a CP4 would shine, big-time. And it is a tempting piece of kit. But - practically speaking - I need the viability of a stronger non-piano engine at present; and the sounds and playability of Yamaha digital piano tones seem to work best for me live. So an S90XS - with extensive piano tweaks - is my live axe of choice. But many here get great results with several other hybrid keyboards - PX-5S, MOX8, Kronos / Krome, PC3x, the Roland RD's, etc.. Looking ahead though, I hope that a degree of SCM piano technology does reach the hybrid instrument level in the next few years - some kind of super MOX or updated S-series style instrument that closes the gap at least a little.
We have just ordered a Mojo, and are looking for an 88 key something-or-other to sit underneath it, We ruled out the Motif and Kronos, they are just too expensive,
We had come down to the PX-5S, the CP4, or the MOXF, A different one seems to be flavour of the month every day!
We looked at the PX-5S, and loved the sounds, but the set- up seemed very complex, and we're not mad about the tiny screen. Maybe once you got used to it, it wouldn't be so bad. The other two haven't quite reached the shops around here yet!
Neither of has had much experience with Yamaha, but have seen horror stories about their user interface, that's why we were drawn to the CP4.
There are two shops within 50 miles which we hope will have all three boards in stock at the same time, but it will,probably be a couple of months yet. We want piano action, good piano and other sounds, easy operation in a PX5s to CP4 price range, Organ isn't important, as we will have the Mojo, and weight doesn't matter, as it's for home use.
You wouldn't think it would be difficult in this day and age, but it's a nightmare. We downloaded the PX-5S handbook, and can't even find layers and splits in the menu! That's why the CP4 looked so attractive, just press a button!
However, at the end of the day, the sound is paramount, so we'll wait and see when stock arrives.
SSM and Keyboard Girl