I downloaded the playable demo and it sounded good. Very responsive. I think the demo version is still on the Post or the Sampletek site. If not, they might be willing to send it to you if you e-mail them.
I'm surprised that Post didn't push this idea more. Now, particularly since you can create an intrument interface in Kontakt 3, it would seem to be an interesting revision of the Holy Grail piano approach that carried it still further. I can imagine an interface of just checkboxes or dropdown boxes that let you choose the source piano for each element. These could be controlled by midi cc's, so you could sit at the keyboard and mx and match elements. From what I understand (I haven't worked with Kontakt 3), you could create this interface yourself, though I don't know how hard it would be.