The question about gate direction on quickdraws comes up pretty regularly on courses. There are two perspectives. The first is that it doesn't matter, place the carabiners on the dogbone however you like. And the second is that it matters and that not doing it right could be dangerous.
Kolin Powick -- the individual who runs Black Diamond's Quality Control Lab -- addressed this in the following video:
Kolin notes that there is a "better" way to put your carabiners on your dogbone. And that better way is to have the gates facing the same direction. He notes that there are two reasons for this:
1) The carabiner gates can easily be oriented away from you when you climb.
Ideally, the spine of the carabiner is oriented toward the direction you're climbing and the gates are oriented away. When you climb with the carabiners facing opposite directions it's harder to remember which way to clip in order to make sure that the spine is facing the climbing direction.
2) The gate can get caught up on the bolt hanger.
If you have set-up your draws with the gates facing opposite directions and you clip the draws appropriately, the gate and nose of the carabiner can ride up onto the bolt hanger. This makes it more likely that a fall will damage or break the carabiner.
As a side-note, the most common way that carabiners break in a climbing application is when they are "nose-clipped." In other words, the nose of the carabiner gets stuck on the bolt with the gate holding it in place. When climbers take falls on a carabiner clipped like this, the carabiner almost universally breaks.
The way you clip and how you have your clips set-up are important. It's easy to see sport climbing as a "safer" form of climbing...but that's not always the case. It's important to do things the right way in order to avoid catastrophe.
--Jason D. Martin