One of the great tragedies of music history is that Mahler never had a chance to record anything. So close, but not close enough. The best we can get is the very old recordings by others who did hear him live, or play under him, and keep our fingers crossed that it's close to what Mahler did. The 2nd under Oscar Fried from the 1920's is revelatory, as is the early Bruno Walter on A&E. Then we have Walter in the 9th and Das Lied from the 30's, Ormandy in 2nd from the 40's. Charles Adler did some. Hermann Scherchen played the 7th under Mahler. Stokowski attended the premier of 8. Haitiink doesn't come close to any of these. Haitink is greatly concerned about beauty of sound, phrasing, and ensemble and quashes the more elemental, edgy, manic parts of Mahler. I don't think anyone alive does Mahler the way Mahler did it. We know from interviews with early NY players that Mahler used a lot of portamento in the strings that no conductor today would be willing to use. Not even hyperMahler conductor Leonard Bernstein used it.
Haitink's first set sounded great, but next to Solti, Bernstein and Levine was seriously underpowered. Beautiful, but lacking in chutzpah. His Berlin remakes were better, I especially liked 3 and 6. But nothing from Chicago has done anything to detract from Solti, Levine, Abbado, Boulez or others who recorded with them.