Hi Paul,
I was about to start a thread to request silent keys for all piano libraries, as this is really an important property of acoustic pianos. Happy to discover others have mentioned this, so as a classical pianist who uses this feature "in real life," I'd like to add my voice too.
There are numerous instances in the piano literature in which we depress a key silently and then hold it using the sostenuto pedal for instance.
A simple albeit temporary workaround would be to require a minimum velocity level (something sufficiently greater than 1 in order to emulate an acoustic piano) to produce a sound. Even if there were no sympathetic resonance as a result, this would still be far preferable to hearing a sound no matter how slowly a key is pressed.
Hopefully this small feature can be implemented soon.
Kind regards,
Albert
P.S. Loving the new Bösendorfer Imperial—many thanks.