Engaged in close combat it is not advantageous to combine key punches or use mouse look. In the type of situations that I am talking about, I currently depend on the 3D sound of the attacking plane to approximate its position. However, without getting a visual, sound tells me little or nothing about attitude of that plane (is he diving in or climbing away, does he have a guns solution, or are you successfully scissored out of range?).
The mouse look does have scalable speed and has been very helpful as you point out and I even have a mini stick on my throttle that allows me to use it while in combat. The problem is the control is very bad.
My conclusion, allowing a more "fluid" customizable pan speed would give precision control and natural feel of movement, and improved situation awareness which is my goal.