With slighty over 200 hour in DB there is still one thing that frustrates me more than anything, not knowing which side you're on in objective mode until too late. For example, if you're defendind on bridge Aura is the go-to medic, since a well placed healing station can determine the match. But what if you end up with her on attack? What if you've brought a skyhammer thinking you would be on defence and end up with his airstrike only being used as a weak grenade (unless the enemy is brain-dead and goes out in the open). I tend to go with a balanced mechanic-medic-heavy (by heavy mercs i mean mercs who are good at killing with their primary, like Skyhammer, Kira, Arty, Fragger, Nadder, Stoker, Rhino and Thunder), so i can't afford to take (for example) 2 medics just so one of them will be useful. It's not a major gameplay issue, it's just annoying.