From your “monitoring while recording” comment I assume (perhaps incorrectly) your concern is based on the experience of latency when recording the output of the MP7se. THAT latency is worse than you will get controlling Pianoteq. With Pianoteq (or any plugin instrument played via midi) there is a tiny bit of midi-based latency, and then output latency. But recording the MP7se, you also have input latency. The combination would be horribly distracting - but it’s much worse than you’ll get with Pianoteq or another VST.

With Pianoteq I find a 128 buffer setting works even for classical work with very fast passages. 64 is of course better. At least with my MOTU interfaces this is no problem with Pianoteq. (FD I use a Roland RD2000 and an RD88 rather than an MP7se). Any perceptible latency CAN be a little distracting, but in this case it’s not even as distracting as trying to play fast passages precisely in a somewhat “live” room. Even in the fully analog realm, latency / delay and related sonic distraction is everywhere.