Remember that the Human Head and brain is like a steady cam in movies. Although you have all that movements of your head and body, most of it is compensated by head and brain, so one would hardly noticing it by dancing and shaking enviroment but by g-forces on your body. You can compare it by what and how you see things when running, and then again running with a camera in front of your eyes. With the camera there is no damping effect, everything is shaking. In real there is not too much affect in the vision, rather in the body. The further away you focus something, the less effect it has. So as it is now it's fine IMO because the vision and focus is not affected but rather the angle is shifting a bit due to g-forces. I think adding roll would add some unnatural feel because even if your head rolls a bit, one wouldn't notice it visually, only by the strain on the body. Slight roll movements is probably what the human brain compensates best. IMO you should leave it out completely.
Think of when trying to hit a baseball, the head is always in a sort of roll position and adapts to the coming baseball. Although you are focusing on the ball, and trying to keep your head still, to not disrupt your angle of vision, it's always an angle. It does not feels strange to the head that it's slightly bent in an athletic position. The vision does not notice it.