An interesting discussion. I live in the dry desert and, with the
soundboard that loses moisture, this caused the pitch to be below 440.
Rather than trying to keep the piano tuned at A=440, I simply checked
the pitches at different sections of the keyboard. It turns out that
most notes were around A=432, so I adjusted the tuning program to
reflect the lower pitch.

In an older piano I assume that the wires have bent at the bridges
making it hard to change the tension.  The piano sounds fine once all
the pitches have been set.

I agree that the dimensions of the wire were selected for pitch at 435
to produce a good resonant sound. I have no experience in tuning a piano
by raising the pitch but it seems best to stay with the original design.

Bill Chapman
in La Quinta, California (Palm Springs area)