Yes, there are... unflattering remarks made.Musicians who played in the New York Philharmonic under the baton of Gustav Mahler, and others who knew him at the time, reminisce about the great composer as conductor and man.
This clash of titans gets spoken of at 32:10

Commentaries I've read suggest the "Bach Klavier" was not a harpsichord, but an un-HIP piano doctored to have a twangier sound.