-Some say it does not reach Ultraxion, even if the debuff shows on the boss. (Need verification.)
DnD does not affect flying mobs, Ultraxion, Deathwing on Madness phase 2, Wing Tentacles and Twilight Assault Drakes, being the foremost in my mind.
-Raid Success may sometimes hinge on AMZ. It's a DPS loss, but may have lead to a faster progression kill. I know this is not the focus on your thread, but just quibbling for completeness for the audience. Notable examples are elementium bolt and twilight onslaught.
AMZ isn't always a dps loss. In the case of bolts, you're generally not in range of anything when you pop AMZ, so that's a moot point. As for Hour of Twilight, unless you can find a way to survive only on external CDs + IBF, then it can be avoided, but it's amuch better idea to use one UH rune on AMZ than lose ~200 potential RP to using AMS.