I know Kobayashi's Third, but in this edition, there is a detail that bothers me: the posthorn seems to be within the orchestra rather than far away. I'm not a fanatic of score's instruction, but I think that this one is very effective and must be followed. I think the problem is due to Japanese engineers. It is curious, but I found the same problem in another Japanese engineered recording of the Third, the one conducted by Inbal with the Frankfurt Radio O. (Denon).
What I like very much of the incomplete Kobayashi/CPO cycle are the first three movements of the Seventh-really nocturnal, dark, demonic, in gourgeous sound!
For the record, the other instruction by Mahler that I think must be followed, is the "Allegro molto und bis zum Schluss beschleunigend" referring to the coda of the Fifth's Finale. Perhaps, the tradition to end the Symphony taking a steady (often pompous) tempo arose when orchestras were not able to come to terms with Mahler's wish. Today, the technical level of major orchestras could allow the correct execution of this passage, nevertheless it seems that the wrong tradition has prevailed (my last disappointment in this sense came from Jansons).
"Tradition ist Schlamperei!"
Regards,
Luca