I know I am quite late to the party but I've just heard this recording. It’s a very beautifully played and moving interpretation (one big, tacky “whoop” and a touch of the ham-it-up school from Ms. Shafer, notwithstanding). I've played it through twice today–a custom I usually reserve for a new 5th, 6th, 7th, or 9th.
I've never understood Haitink's Mahler (RCOA and Berlin series)–the most recent Chicago issues I've simply found appalling (boring). Of the many things (mostly German repertoire) I've heard from him, I have preferred, interestingly enough, his Vaughan-Williams and Tchaikovsky cycles.
Like many here have wished already, I'd like to hear a new M9 from him.