Pianoteq is great! Apart from the "standard" piano setup, I aslo use Pianoteq as a practice tool for organ with the various harpsichords presets. Indeed, in the baroque era, double manuals harpsichords were used along with a pedal-harpsichord (on the floor) for organists to rehearse.  (see: http://www.youtube.com/watch?v=Tv64B1bG5jA)

Unfortunately the current Pianoteq "standalone" cannot play the same note more than once from different midi channels, which make sense in the context of a piano but not for harpsichords that routinely have two (or 3) sets of strings and often two manuals.

It is possible to circumvent to problem by using Pianoteq as a VST. In my case I use Synthedit (VST Host) and send the 3 keyboards (pedalboard) midi messages to differents instances of Pianoteq with different voicing characters.  It works but there are limitations:

1) high CPU usage, I had to turn off reverb
2) no sympathetic resonnance (and other tone rich effects) between the 3 keyboards)
3) Since the 3 Pianoteq are usings similar models, playing the same note on different manuals at the same time results in an unnatural sound (that even happens with Blanchet and Grimaldi playing together)

Extending the mathematical model to allow multiple string sets on the same soundboard would be a dream!