I'm very interested to hear the effect, but changing the concert pitch goes beyond changing just the sound. Pitch also affects the performance itself and altering it makes it no longer the artist's performance. I'll need to hear it before I know how to feel about it.
Consider a pianist sitting down at a piano tuned to A=440 and playing some music. Then retune the piano to A=432 and have them play the same music. The pianist will hear the lower, more mellow sound of the instrument and likely adjust the tempo, dynamics and phrasing of their playing.
Now consider a recording of the performance at 440, and shift the recording's pitch to 432. What should we make of it? It doesn't represent how the performer would actually play at 432 tuning. It would be an artificially created performance that didn't happen.
I know that some will feel, "you can do whatever sounds the best to you", but often I am genuinely interested in the performer and how they interpret music. It raises questions about the nature of music and performance. We have reached a stage where someone can say, "My favorite Beethoven Eroica is Furtwangler's 1951 recording, retuned to 428 and tempo increased 3%". Would that still be a performance by Furtwangler?
I think your points about pitch impacting tempo, dynamics, and phrasing are extremely deep and open onto the basic questions of musical interpretation. I appreciate your forcing me to sit with them. I wonder whether the answers are to some degree unknowable, particularly if the artist is dead.
I'm reminded of the harpsichordists vs the pianists on Bach. Is it Bach if you're playing it on an instrument he never imagined? Or to choose a directer analogue - European pitch varied wildly before A=440 became the international standard, with artists as eminent as Verdi joining the c=256 movement. Is Furtwängler's 440
Otello really
Otello, if Verdi wanted 432?
I think that historically informed performances are extremely rich and rewarding, and the movement has produced a lot of knowledge that's deeply worthwhile and gratifying. But I think it also has its limits, and that we modify recordings all the time, through the tuning of DACs, amps, and transducers—to say nothing of the great EQ revolution currently underway. I think that the artifice of listening to the Mass in B minor with my KSE1500 while jetting across the Atlantic should not be lost either.
I don't necessarily think that Bach is unknowable or unreachable outside the Sunday morning pews of an eighteenth-century Lutheran church. But I think the comparison gives us some context around the acoustic re-production of sound. And as always, Jason's Scotch Mod is an important baseline: we are ourselves so changeable and subjective, day to day, hour to hour, that objective experience will always be a challenging hill.
This kind of pitch alteration is a novel change, and one I'm grateful to Mike for championing. But it's just one of many ways we remove ourselves from composition and from performance.