OK, Freelunch. I guess you're taking my 'every little movement of the head' literally, so I concede that 'every movement' won't translate to a stereo image shift. I'll amend to say that reasonable right to left head rotation will result in image shift.
It's basic Recording 101 that directional mics will have image shift if you rotate the stereo pair. I record with my Schoeps cardioids on a stand, the imaging changes even if the stand gets rotated a little bit...it happens all the time when people trip over the legs on my mic stand at a venue where I set it up DFC and I have nobody to help me block.
However, the point of my original response was simply to state that omni's can be more forgiving than hypers when they're mounted in a hat.