I sampled audio tracks of the Artek M7th on their website and didn't find it particularly impressive. But you never know...
I only saw a sample for the third movement scherzo, which I thought sounded quite good.
When Abbado conducted it in Edinburg, England, the first movt. clocked under 20 min. It was a super fast performance.
I don't get that, as there's absolutely no indication in the score that the first movement should go like the wind. In fact, Mahler simply writes "Allegro con fuoco" (with fire) at rehearsal figure 6 - the main body of the movement. "With fire" doesn't mean lickity-split. More to the point, there's a spot that indicates that the movement CAN'T go super fast. To be specific, the 10th bar of rehearsal figure 14 indicates, "a tempo (sempre l'stesso)"; with the added comment that a half-note before, now equals a quarter-note. In other words, there should be no perception of the music slowing down at all. Abbado - and many other conductors - execute a massive slow-down there. Yet, the score very specifically says not to do that!!! The music simply goes from cut-time to 4/4 meter there. One moment your conducting two beats to the bar, and in the next moment, you simply conduct four beats to the bar - with no change in tempo.
Even more to the point, the first movement of M7 is one Mahler's very most complicated in terms of polyphony - contrapuntal lines, in other words - and harmony (which all happens at a relatively quick harmonic tempo). To me, Boulez's 23 minutes sounds just right.
Barry