I saw this forum post: http://us.battle.net/d3/en/forum/topic/12329613230
The gist of the rather long post is that you get far more legendaries by making "chest runs" through story missions, like Act V Mission 6.2, than you will by killing anything. It recommends stacking survivability and mobility and outright ignoring all mobs (especially elites) and treasure goblins, focusing solely on looting chests. The results it claims are on the order of 6 legendaries/hr as opposed to approximately 1.7 legendaries/hr playing the game "normally".
Some people in the thread says it's fake. I want to know if chest farming like this is worth it in any way.