Purely based on damage, I think it's safe to assume that 1% haste > +3 attack (right?).
However, as all good DD know, sometimes you pull hate, if only for a moment, and the mob swings at you. Clearly, in that situation, Denali's defense benefits are pretty big. If you're dead, DoT tends to go down ...
So what should I be doing? Take a few endgame monk DD (non-chi) situations: birds merit, Kirin Zerg, sea/sky/limbus farming (non-god).
I've essentially just used denali for all DD situations in the last year, but now I'm thinking maybe that's not quite the right call. I now only use turban when I'm expecting to tank and need every drop of shadow speed, like Salvage or JoFaith.