Like you, I was excited to try out PianoOne when it was released a while back. I mentioned on the other thread 'tuning electronic pianos' that I believe the future is hybrid sampling/modeling. Although PianoOne claims to do just this very thing, it falls short on both fronts IMO.
First, the sampling is not nearly detailed enough in terms of velocity/tone changes (and at only 160 Mb, what can we expect?). All the notes, whether played at soft or loud volume, have a similar character to my ears. The math engine might be outputting the correct interpolation volume between 0-127 midi values, but the tone or piano color does not change nearly enough as one plays up that velocity scale.
Secondly, the acoustic resonance modeling is not up to the standards of Pianoteq. The sounds and frequencies heard 'in between' the notes, like soundboard noise, sympathetic vibration between strings, damper resonance, etc.) does not sound as realistic as Pianoteq does IMO.
So, in other words, this unfortunately is not how to do my hypothetical perfect hybrid. For that to be pulled off, one would have to physically hand the equations of Pianoteq (which are no doubt closely guarded) over to a reputable sampling company like Synthogy, Galaxy, or True Pianos. Or, hand their beloved samples (which are also very proprietary) over to the Pianoteq team and have them somehow integrate the two. I have no idea how THAT would work, but this IMO is what needs to be done to further virtual pianos to the next level.
I tried heavily-handed to merge PianoOne and Pianoteq inside Reaper so that my keyboard triggered both. PianoOne provided a decent pianistic-attack sound and Pianoteq provided the beautiful resonance. I was partially successful, but the two libraries are too disparate to morph into my 'ultimate' piano. It needs to be done professionally at the software level. And the sample library needs to be in the Gigabyte range, not the Megabyte.