I prefer fight while in flight
Talking about a concept slowing down gameplay 
I just remember how much more actions/options it took me in that one game “nobody knows” to fight: keycombos for me: move left, crouch, shoot while crouch, after a split second standup again, sprint move right to go out of fireline for a split second (like neo ;)), crouch again, shoot while crouch, stand up, stand still for split second, shoot, move right, etc. So i crouch, stand, sprint and shoot, and i am also able to use my environment, because my character is very responsive and it doesn’t take ages to take cover again; and i have various ways to incorporate sprint, you can mix it up intelligently whenever you want (notice the decision level), but it requires stamina bars, and those are silly 
DB in contrast? Well, i am still trying to find out. Not to be overly negative though, i just want to state that if you put that concept of splitting movement and firefights in place, that it might not be so much fun. Because ultimately it will result in a much slower firefight. It just doesn’T blend that well imo.