Anyway, since I'm flying her a lot of time lately, this thing bothers me and I think I'm not the only one. The HUD is affected by only 2 axes of 6DOF movement, while completely ignores other 4. It's affected by Yaw and Pitch but not by Roll, X, Y and Z axes. Please, see the attached video:

https://www.youtube.com/watch?v=g7z2BRgAQdA&

EDIT1: this is how it should be:

https://www.youtube.com/watch?v=wJ1UWrOfxhs&feature=player_detailpage#t=33
(from 0:33)

EDIT2: Oh, and I forgot to mention that I'm using the Head Range Plus mod too.