I would love to see some direct comparison music. Listened to one quick guitar riff on youtube that I could find and 432 just sounded out of tune to me. Which, I suppose, it would be.

I question how much effect this would have over time. 8Hz would be a shockingly small amount of change to not have accidentally stumbled on to this being "better" hundreds of years ago. So I'd wager it's maybe something to do with the music sounds just enough "off" from normal that the mind becomes more engaged with the music.