There is a small amount of noise that is made as the plunger is striking the key. In normal circumstances the sound of the piano itself would completely drown this noise out.
With the type of recording you are trying to do however, this noise might be picked up by the microphones. Because the noise should (theoretically) happen just before the actual tone is produce by the string, it
may[/b] be possible to edit out this noise.
I spoke with the engineers myself yesterday, and they just didn't seem 100% confident in recommending it for the purpose you are considering. (excellent idea though...) They aren't confident in saying it wouldn't work either--they just aren't sure, and they are trying to avoid misleading you into making a wrong decision.
Even end-users would have a difficult time discerning whether or the the system would be usuable for your purposes. Unless they also sophisticated recording equipment, any recording they do for you may miss something yours would pick up. Conversely, if there's isn't set up just right--it could be making noises that a better set-up might eliminate.
In your other thread, it sounded as though QRS quoted you essentially a wholesale price. (thanks a LOT to them for that...) If you can get it for close to that, then it seems worth the "risk" to me. --but that is just a personal opinion!