A couple years ago the (now) department head in my physics department was working on physically modeling a piano. The mid ranges sounded pretty good, but the top and bottom sounded pretty bad. I think he improved on it eventually, but I'm not sure if it ever sounded all that great. He may still be working on it, as a matter of fact, since I think there are still a few pulled-apart upright pianos in the basement of the physics building. If this really does use physical modeling, then I'm impressed that it sounds as good as it does.
That being said, I took piano lessons from the time I was about two and a half years old (well, I doubt you can really count what I took when I was that young) all the way through high school. And honestly, I've always been pretty happy with every single synth piano sound I've ever had, from the crummy sounding Ensonique, to the only slightly better Roland XP-80 that I still have, to the free piano sounds that come with Kontakt 3.
In fact, the free piano sounds that come with Kontakt 3 sound so great to me that I could never imagine needing to upgrade to something better. If I want to feel like I'm playing a real piano, I'll play a real piano. If I only want it to SOUND like I'm playing a real piano, then the Kontakt free pianos with any keyboard seem to do just fine. I would be fooled by them. I don't think I could ever hear something done with the Kontakt pianos and say "oh, that's not a real piano," unless I specifically recognized the sound, since I use it a lot.
And what's all this "the instrument has remained fundimentally unchanged. . . until now," on the Roland website?