Herr Polarius,
I have a pair of Bose noise cancellation headphones. They cost me a good chunk of money too.
By and large, both David and myself have been pretty supportive of Boulez's Mahler. I like most of them. I had some real issues with the DG studio release of M2, but I felt that the "live" performance issued on DVD addressed all those issues (especially the organ). David was probably the first critic to be supportive of his M4 with Cleveland, which was - up to then - receiving luke warm reviews at best. Now everyone seems to think that it's pretty good. I've always been a big fan of his M6 from Vienna.
You seem to keep coming on to this notion of European vs. American critics (maybe it's just David you're after). Well, let me make a generalization that seems to apply to many critics in general, regardless of where they come from. Many critics say that such-and-such artist is great; therefore, everything that he or she have recorded must also be great. Both David and myself attempt to evaluate every recording on its on merits, regardless of who the performers are. You may not get that impression, but take a look at some of the reviews that David has written for Boulez's Mahler cycle - most of them are quite positive.
As for myself, I believe that I addressed your question as objectively as I can, without repurchasing the Boulez "DLvdE" (no way is that happening) to comb through it point by point. You asked the question, I provided my answer. It would be an adaquate "DLvdE", if we lived in a world of few choices. But as with all of the works by Mahler these days, there are tons of choices to comb through. I'm wondering if you're familiar with Bertini's "DLvdE" (?).
To me, Bertini's "DLvdE" is very controlled and very careful - somewhat like the Boulez (I think the big, single F horns that the VPO use aren't the best for this particular work though), but receives far better vocal contributions from Marjana Lipovsek and Ben Heppner. Michael Schade is just a complete non-starter in my book. So, if I wanted a more up-to-date, detailed, controlled, subtle, "German" (and frankly, I don't care where it comes from) performance of "DLvdE", I'd probably reach for the Bertini. I think that Karajan and Giulini are remarkably good as well. Singers do matter in this work, and I feel that "der Abschied" should not be treated as an extended operatic aria. The question as to whether Urmana is the right kind of voice for "der Abschied" or not, is greatly compounded by her having been recorded too closely. I find it uncomfortable to listen to, and that has nothing to do with which speakers, or which headphones I'm using. Once again, I could live with it, if there weren't tons of other recordings already available. Others have brought up Baker/Kubelik on Audite, and that's a very musical place far anyone to start.
Anway, now I have to run.