As I've mentioned, I always listen to 2-channel music in surround, using DPLII, etc., to extract the ambience(always present to some degree)and send it to the surrounds where it belongs. Your comment inspired me to listen to Karajan's 10th now and rapidly switch between surround and stereo. There really is a major difference and the stereo does give it an excessively flat and dry character, which surround pretty much corrects.
Incidentally, your mention of Skrowaczewski's 10th led me to search my resources. I found a small college library which had a 2-disc set of his 5th and 10th performances, which I requested and should get in 3-4 days.
Edit: I might also mention Mehta's Mahler 5th with the LA Phil, which I have.
