I've recently completed research which led me into writing a paper to be published shortly in being asked to talk to the Friends of the London Mozart Players about "The Colour of Tuning in Mozart's time"
A video of the lecture is on https://www.youtube.com/watch?v=bt-ttLY5ex8
. It was as a result of Arthur Ord-Hume writing in respect to 18th century barrel organs that the tuning made one wince, and that it was intended to, that the penny dropped that Mozart should be auditioned in no less than 1/4 comma meantone. Upon doing so, his piano sonatas revealed most interesting results - it was like developing a photograph, and Mozart's Fantasias in F minor made more sense on two ranks of pipes, as written for, rather than the muscular interpretation we've all enjoyed on full organ with equal temperament.
According with and making audible Schubart's description of the character of each key, written in 1787, I wondered if we might have got the wrong end of the stick with regard to Bach's 48 preludes and fugues for well tempered clavier. The lecture includes demonstrations and those with meantone tuned organs might experiment starting in C with a plain diapason, registering the keys known to Schubart for increasing brightness, and registering the dark keys as in the lecture demonstration, with a mournful Stopped Diapason or Leiblich Gedakt. The cycle of compositions seems to make sense and to work, indicating that it might not have been written to celebrate new tuning but actually to exploit the emotional "Affekt" of each key.