I am also having this issue, using a G700 here. The problem is not camera speed per se, it's that the camera moves inconsistently. I will go to make a turn around a corner and end up spinning around twice and facing in a random direction, frequently looking straight up or down. It's like they have mouse acceleration on, but the curve on the acceleration is more like a vertical cliff, once you move it just a little too fast it accelerates to the point where you lose control of where you are looking/running.
