Every key has a different color, especially on the instruments of Chopin's day, which were less tempered (I don't think I'm making that up.) Wild's transposition of op. 25 no. 1 to G-Flat puts it more in a warm Schubertian world (Just think of the G-flat impromptu, which Horowitz first recorded in G major because of his ignorance and faulty edition!) I can agree more with 25/1 than with 25/12.
I do not agree at all on 25/12. B-flat minor in this case is a deeper keep, but not a darker key. It is a harrowing force of nature perfectly suited to c minor...and history is on this side (consider the connotations of Mozart's K. 491 piano concerto, Beethoven's Pathetique, 3rd piano concerto, 5th Symphony, final piano sonata, etc.)
I did enjoy watching this interview, even if it makes Wild look a bit dull of wild (Ouch, failing pun...)