Hello Inky, and welcome to these boards. You may recognise the forum software from somewhere? :)
AFAIK Busoni's principle rage was reserved for Wagner, who annoyed him so greatly that he wouldn't even name him in his lectures.. referring to "that man" or "Herr W". Considering that Busoni had, by that stage, emigrated to Berlin to lecture, this was something like criticising the home side. His disgust with Wagner arose from the "damage" he believed Der Meister had done with TRISTAN & ISOLDE, eating away at the traditional concept of tonality. I believe he did respect Schoenberg as a man, and for his serious-minded approach - even though he saw no future himself in dodecaphonic experiments.
Well, whatever Busoni might have thought of such experiments, the first published fruits of Schönberg's appeared only in 1924, the very year in which Busoni died, so it would hardly have been possible for Busoni to avail himself of sufficient opportunity to form a considered opinion of Schönbergian dodecaphony by studying his dodecaphonic scores and listening to that music. Whilst you are correct in referring to Busoni's criticisms of Wagner, any "damage" that Wagner might be thought to have done by "eating away at the traditional concept of tonality" might as easily be ascribed to that which Busoni himself did in works such as his second sonatina for piano. That said, Wagner did seem rather to shrink back a little from the loosening of the bonds of such traditional tonality, especially in his final completed work
Parsifal, just as Strauss was later to do following
Salome and
Elektra (and, whilst Busoni certainly expressed various reservations about Strauss, he not only admired him as a conductor but also described
Salome as "a throw of genius"). Another example of drawing back from the brink of a perceived abyss is Ornstein who felt the need to do so following his sonata for violin and piano of 1915. It would have been interesting to discover what Busoni thought about Schönberg writing his E flat minor chamber symphony after quite a few dodecaphonic works had Busoni only survived for a further 15 years or so.
I wholeheatedly endorse your encomium for Busoni's final opera; incidentally, in addition to the Beaumont completion, Stevenson also made one (well before Beaumont's, I believe) but I've not seen it and it's never been published.
