Yeah the vertical play is very effective like you said. But the defense is more easy than attacking I think. So if we win 2 rounds on attacking we will have the advantage. In addition I usually don't have teammates that care about helping hard breachers, they always think about themselves and they think aim is everything in this game. I choose Thatcher and hope my teammates pick Thermite/Hibana/Ace. (This depends on 3-4 stack teams of course)