snilf,
First of all I don’t have a piano in my RV. I don’t even have an RV. Those are my initials, and I am (or was) a pianist.
I agree with your choice, btw, of the Furtwangler Brahms 1st, especially in the Pristine.com pressing. Your point about Mahler is also very well taken: It is so much about the sound. Which speaks to the question so many have addressed here. I think I (we) get in trouble when I turn the set on looking for sonic wonders.
Again, as so many have said, if the initial motivation is the song or piece of music, the result is much happier.