With a mouse you can rotate your view much faster than with a controller, nearly instantly.
You can easily see this in game. Mouse users can jump over a target and rotate backwards immediately. A fireteam mouse user can rotate immediately and shoot at the predator.
This is a game changer.
Thus, turning mouse speed could be limited to what is possible with a controller. I mean a hard limit, maximum angular velocity and maximum angular acceleration - no matter the dpi of the mouse.
What do you think?