Agreed. I don't mind the 12:30 Adagietto that much, but it is excessive. People make a huge deal over that, yet they say nothing when the slow movement of M6 gets stretched to 17 or 18 minutes. What they fail to take notice of is that the slow movement to M6 is marked "andante moderato", and that the word "langsam" doesn't appear anywhere in the movement. Meanwhile, the Adagietto has passages marked "sehr langsam" all over the place.
I love the two inner movements of Vanska's M6, but the two outer movements have their own, unique problems. When I listen to it in its totality, I don't mind it so much. I may dump it some day, as the Paavo Jarvi one is very good from start to finish (better cowbells on the Vanska). I know we're both looking forward to an eventual Adam Fischer one. Rumor has it that Reference Recordings may start issuing Honeck/Pittsburgh Mahler. I have a feeling that's just wishful thinking.