Myself, members of my community and a couple of people on the BI forums have noticed a sudden shift in the way TrackIR behaves in game since the 2.06 update. The profiles that we have been using for years in some case behave completely fine in the TrackIR software but have odd results in game.
We've noticed that head movements are a little more sensetive when in vehicles but when dismounting to use it as infantry that even tiny movements cause the characters head to spin more than 360 degrees in some cases, but turning down sensetivity causes the view to become heavy and sluggish in vehicles again.