Yeah, but Gatti's finale doesn't hold a candle to Karajan's (too little bass drum, for one thing), and the RPO strings are thin and lack-luster in the famous Adagietto. I'd also be curious as to precisely where the BPO is supposedly falling apart on the Karajan M5 (timings or bar numbers, please). I'm usually extremely sensitive to poor playing, as you know.
Karajan was extremely proud of his recording of the 5th Mahler, flaunting it in front of Carl Orff. I think he was right. For once, he was able to get beyond himself, and just let go. But I also feel that it's sufficiently anal in regards to detail.
Karajan's M6, on the other hand, may be superior in terms of precision and details, but it's conceptually a mis-fire. It's a case of missing the forest for the trees. The opening march is simply too fast and furious - hardly anyone does it that way anymore. But more to the point, the outer movements are fast and furious, while the two inner movements are simply too slow. I could possibly excuse all that, if it weren't for the fact that Karajan really almost drags the numereous and lengthy trio sections in the scherzo movement. And while the Philharmonie may be a better location for going after precision, this is simply the start of a long line of recordings that really almost sound like dog-doo. On top of that, the hammer strokes are sadly underwhelming. What's the point of getting tons of little details right, if you're going to miss such an obvious and major one? Like the famous Solti Mahler 8th, this is a recording that I've tried to make myself like over and over. What I've discovered is that IF I want an M6 with a fast and furious beginning (and I don't), I'll reach for Bernstein everytime - either one of them. I will say this much on Karajan's behalf: just as with the MTT/SFSO M6 recording, the Karajan one does work better if you switch the two inner movements.
Barry