Thanks! This is interesting.
Pianoteq is without a doubt the best sounding piano synth on the market today. Uses all sorts of interesting physical modeling algorithms (including string-to-string resonances, with a more-than-first order model...), unfortunately, unpublished. ;)
If you're interested in chatting about sound generating software and algorithms, feel free to shoot me a line. "Also, do I remember you from ec-discuss?"
https://www.pianoteq.com/