This should be greater, especially at lower speeds. In real life, you can rotate 45 degrees easily, 50 degrees if you're flexible and not trying to move too fast.
The use of this is a fundamental part of CQB, as it's bad practice to be looking around with your head independent of the gun, even if your movement direction is different than you are looking.
This might even be useful for people using VR headsets like with VorpX, or if BI ever adds native headset support. That will of course allow both torso movement and body/leg directional movement independent of each other.