I have compared them. Pianoteq is far superior when it comes to dynamics and responsiveness. Not only does it sound real it feels real. Being a pianist myself, that makes all the difference. If you are a producer and you just wants something that sounds good than, truepiano should suffice.
I have both. As Anthony said, Pianoteq is particularly good if you are a pianist. Truepiano is really good for a solid piano sound with a little less CPU overhead. One of my favorite things about Pianoteq, though, is since it's a physical modeling instrument, you can do some pretty cool things with it. It will read Scala tuning files and I recently used it to compose a piece for microtonal piano that worked amazingly well. If you try to do that with most instruments, it just detunes the samples with all the artifacts entailed. However Pianoteq retunes the "strings" so you continue to get a realistic piano sound but with different tunings.
Thanks guys, yes I tryed Scala before this post, but i did't find where to import scala file. But I take a look on Pianoteq page again, I had Stage, not Standard version. There's not available to do that. Primary problem solved. I'm exclusively working in Max, controling Pianoteq with sequncer along live piano playing, after that mixing it with synchronized sampler in Max, and all maped on one piano. It would be nice make a retune under one roof. Max Gardener, thank you, I will try your recommendations. Already I don't understand how to send retuned scale to Pianoteq, if I must generate someting like scala file from Max, or I can do that directly to Pianoteq VST inside patch? Maybe I will have more specific questions, if I can.