Currently testing the 1.64RC. Using a 5.1 Logitech G430 headset. When i first started playing, right away noticed a difference with sound. Not sure whats in the changelog, but i think the following is a bug.
When moving forward, and your guy is calling our commands (Return to formation, Target 200M, etc..) it sounds like your player is calling them out from behind you. However if you move backwards, then it sounds like the sound is coming from in front of you (not the actual player.