Well guys, it's greatly a matter of taste - or lack of taste on my part. I think that added bass drum strokes, while certainly garish, help make that ending sound more conclusive. I think what could work even better, is not to have any timpani or bass drum on the very final stroke at all, and, instead, bring in extra trombones, horns - and a second tuba - for the final chord only. The point is to have a bigger, more saturated brass sound, but without having anyone actually blowing louder. In other words, a terraced effect without greatly changing the tone color (Mahler wants it to sound un-strained).
You see, back at the climax of the long brass chorale - after the symphony's final cymbal crash - I would increase the trombones to six (it's two-part writing for the trombones there), and the horns up to 12 or so. I'd also double the tuba, so that the sustained "D" pedal point could remain unbroken (they have to breathe!). Then I would leave out that same extra brass until the very final chord of the symphony. I think that could work very nicely.
