I'm never too keen about Yamaha's pianos. They are all a little too bright. Bright is good - great for jazz and rock. But Yamaha is more than just bright - I think it has something to do what the post-recording processing. The higher registers doesn't sound real. The loop is too short.
The PLG150-AP also sounded like that. I'm glad that they extended the loop, but still it lacks depth. Hard to judge by the demo - must try it out.
I think they sampled the Yamaha C3 Grand, which already tend to be bright. It is probably the same original sample set from the S700 3-velocity layer piano, except they lengthened the loop in this case, but I could be wrong. I don't like the S700 at all, but that's my personal preference.
I personally feel that if they sampled with more depth (a Bosendorfer, or Steinway which is brighter but still more mellow than the Yamaha C3), obtaining a brigther sound can always be adjusted by EQ. You don't lose too much clarity. But if the original sample is already too bright, EQing to make it darker doesn't work quite as well as the depth of the sample is already lost no matter how you EQ it. It was never there in the original sample in the first place. That's why I prefer the Roland pianos to the Yamaha's - synth-wise.
What do you think?
As for the S90 ES, they added the S700 piano. Too bad - nothing much new in it.
Still having said that, I probably would still get a Yamaha keyboard compared to a Roland just for the touch. Sound wise can always midi to a softsampler or a module (Roland, perhaps). If only we can mix and match our custom keyboard...