Sorry for resurrecting this 6-year-old post, but I'll add my two cents on Kobayashi's Mahler as it's what I've been hearing recently, as well as reply Barry's unanswered question as to whether his JPO M8 is worth getting.
Well, maybe I'll answer Barry first. It is an absolutely fantastic Mahler 8th. I have probably never heard a more passionate and dramatic prelude to the second part, where the strings absolutely tear into their instruments at their peroration at "etwas bewegter" (did Kobayashi misread it as Ausserst bewegter? Whatever--it's thrilling!) In other places, Kobayashi's interpretation is wholly passionate and committed, and the fantastic orchestra and chorus play and sing with considerable aplomb. The Chorus Mysticus is taken very slowly, but all to the good for the music's transcendental excess. A bit more prominence from the trumpets at the very end would have been nice, but otherwise this is faultless. (Kobayashi even adds a cymbal crash to the very last note!) And the audience goes nuts at the end.
I'm not a general fan of Japanese soloists--having heard some of them almost ruin the otherwise fantastic Inbal M8 (the most recent one)--but it seems that Kobayashi has assembled a very fine cast. The tenor and baritone are particularly outstanding. On the debit side, an unfocused and hoarse Czech bass. Exton's sound is, as usual, fantastic. I read from another post somewhere that someone was worried about getting this M8 because of the rushed and perfunctory Bertini M8. But Kobayashi is not Bertini. Buy with confidence.
As for other Kobayashi Mahler recordings, I have heard his Czech PO 1 and 5. Both are pretty terrific, though in some spots of the 5th symphony the heavy brass fail to penetrate the texture even when they carry the melodic line (a typical CPO problem, I find). But as far as Kobayashi's interpretation goes, he's absolutely spot on.
I see that Barry has recommended the CPO 3rd. I can't wait to hear it, as soon as I get my hands on a copy.