Stretching a resolution on a screen
Changing your m_yaw will keep the relation between the distance you move your mouse and the amount of pixels your crosshair moves on the screen the same. Usually being used to a sensitivity means that your brain associates distances on your mousepad with distances on the screen, not with angles you turn ingame. So this calculator will help you keep your muscle memory when it comes to flicking to enemies that you see on the screen.
However, it will change the distance you need to move your mouse when turning beyond the screen, because it changes the distance you need to move your mouse per degree ingame.
You will have to choose between muscle memory on the screen itself or beyond the screen (I choose on the screen, since you need to avoid being shot in the side or back anyway).