I use Pianoteq live at gigs in a 'rock band' (lol, that phrase sounds so quaint) and so Pianoteq is running on a laptop and I'm playing it from a MIDI controller keyboard, with a MIDI cable plugged into the computer's MIDI interface.

One nasty thing that can happen in this scenario is that your lead guitarist trips over your MIDI cable when they're running around the stage showing off, and it gets disconnected, leaving you with "stuck notes" on Pianoteq (it got the Note Ons, but the cable came out before the Note Offs reached it)

The original MIDI spec has a solution for this: the FEhex "Active Sensing" byte.
Your controller keyboard spits it out every few hundred milliseconds, and if the sound generating device stops getting it after a few hundred more milliseconds, it does an "All Notes Off" type action.

I wonder could this functionality be built into Pianoteq (configurable to be turned off if not needed, in case it uses too many resources)?

Another little thing -
there's also a MIDI "Tune Request" byte (F6 hex).
My Kurzweil MIDIboard even has a dedicated button for it.
The idea was generally that if you pressed it, MIDI synths with analogue VCOs would run their "autotune" calibration routine.
Perhaps Pianoteq could respond to it by reverting to a given temperament (default choice: equal temperament) ...
Might be handy on stage or even in the studio if you want to play something in a fancy temperament, then revert back to an "ordinary" one quickly. Another way to respond to the F6 byte could be to revert to a configurable pitch reference (default: A440)? And/or reset the string unison/detuning parameter to 1.0  (instant recovery from honky tonk!)
In fact I can see the little config dialog for this in my head right now ;0)