Actually no matter what kind of head control method you use, the limits of movement are the same.
In that sense it doesn't matter if you use trackIR, Freetrack or pan the camera with the mouse, there are certain controls in some bombers situated at the aft portion of the left hand side console that are obscured by the pilot's seat.
This certainly happens both in the Ju88 (fuel cocks, radiators barely visible and i think there's something else too which eludes me for now) and in the Blenheim (the carburetor heat controls and maybe something else as well). I haven't checked the He-111 or the Br-20 yet.
If you hover the mouse over the right place you still get the tooltips and most of these controls will either be mapped to keyboard if they are critical (the Blenheim carb heat) or will be used only twice in each mission (during start-up/shut-down), but it would still be nice to be able to look around and see/activate them without having to play hide and seek