Interesting comments on nausea and vertigo. Having to consciously override what your senses are telling you must be an odd experience.
I don't know if it has anything to do with it, but the planes I practised my initial flying were all with canopies, making it natural to look into the turn simply by lifting one's chin instead of peeking around the frame the cockpit structure creates in some airplanes.
My only real life 'piloting' experience to date has been a very brief one ('experience flight' in a glider) and I don't recall exactly what I did with my head except looking into turns to check for other aircraft, but I did find the view of the Cotswolds laid out beneath me was a a bit distracting when it was time for me to take control of the thing. It wasn't a feeling of vertigo but more one of being overawed. I could probably have used another 10 minutes of "ooh-ing" and "aah-ing" beforehand.
I really should try and get in another trial flight one of these days. In the meantime, looks like I could get the opportunity for a couple of training sessions in aerial survey ops which will make a bit of a change from the usual marine stuff. My outfit uses Cessna twins for this purpose and I'm wondering what back-seating in one of those will be like for a few hours. They tend to fly lots of parallel survey lines with uncoordinated (skidded) turns at the end to keep the sensors pointing downwards (unless they've upgraded their mounting arrangements). I reckon the novelty of doing this for hours on end, head down in a laptop, may wear off pretty fast.
P.S. As expected, the head tracker certainly doesn't make sim flying in IMC any easier, especially if I move my head around to glance at the keyboard or to try and grab a slurp of coffee!