Not long ago I watched
"Pianomania",
https://en.wikipedia.org/wiki/Piano mania , tuning the
grand piano by this documentation has less to do with A = foobar Hz.
More important seems to be the consistency of the grand piano's
mechanic and tuning within whatever is the chamber pitch.
Apart from this, a friend of mine, Achim Jaroschek, a much praised
German Jazz pianist and drummer, a while back owned 2 Bechstein and one
Baldwin grand piano. All grand pianos were tune relatively good to his
taste, but we were unable to do a good home recording, due to the
missing microphones for this task.
What ever the chamber pitch might be, more important is the consistency
of the tuning, not necessarily regarding the pitch, but regarding the
emotions of the piano player, regarding the consistency of the grand
pianos behaviour and apart from this, as soon as you want to record the
piano, much more important is the available gear.
I really doubt that the tuning of the chamber pitch by itself does much
affect the result of a performance.
Indeed, decades ago, when I used the Roland MT-32, not with it's
factory sounds, but with self edited sounds, that should emulate
analog synth, I several times tuned it a little bit below 440Hz,
because this added more warmth, while all the other analog and digital
synth wer tuned to 440 Hz. However, when ever I tested pitches <> 440
Hz nobody ever listening to the recordings, including myself, felt
better at any pitch higher or lower lower 440 Hz.
A tuning that differs to 440 Hz could be important for live performance
of classic orchestras for several reasons, but is most likely is
irrelevant when making music with electronically instruments. Apart
from this the tuning usually is higher than 440 Hz, due to
loudness/transparency/brilliant,
https://en.wikipedia.org/wiki/Concert_p
itch#Pitch_inflation .
In rock music guitarist's, I'm one myself, sometimes tend to either
tune in relation to 440 Hz all strings a half tone lower, I don't, or
as several people from my generation (generation x, aka grunch) and I
do sometimes, drop the low E string to D, IOW just one string a whole
step lower,
https://en.wikipedia.org/wiki/Drop_D_tuning , however, A
still remains at 440 Hz.
PS: Consider a drop D tuning more like something compared to an open
tuning used for e.g. Dobro played on the lap or sometimes for
bottleneck played guitars. I prefer to play bottleneck without an open
tuning. Anyway, all tunings are usually related to A = 440 Hz, they
just fit to a harmony, Dobro played on the lap often is tuned to G
major, when played completely open. This at least was what a friend
always used and it seems to fit to most of the new and classic blue
grass music he used to listen too.