In reply to Up High:
If we take the notion that we clip like in this picture:
http://www.mooneymountainguides.com/blog/wp-content/uploads/2013/06/IMG_134...
With the rope biner having the gate on the right if the rope is going to the left, imagine a more extreme situation whereby that rope went at a bigger angle to the left, then went under tension, in that configuration the gate is a long way from the bolt, which is good. You don't want the bolt on the gate.
Seems modern thought is to have them facing the same way, that's what I do, partly because thats just how they come. There's a stack of people that oppose them, and they're all fine...
If you're using removable hangers and wiregates, you spend a bit more time thinking about this. (Some people go as far as flipping the top biner,
http://www.pointperp.com/Images/IMG_5420_clipped_carrot_bolt.jpg )