helmet camera feels good when i'm cruising around a track. but racing, you miss the apex, you get powersteer on corner exit (or going sideways in general). the look around makes it more confusion imho.
also ("technically") you have to recalculate the direction of the car based on where the interior points relative to the track. when moving the real head human sixth sence (maybe it's fifth?
) knows that with usually high precision relative to at least the interior, without thinking... and also that the position of the car relative to track doesn't change just by moving the head.
in simple words, sometimes it feels like everything moves, when it's just the automatic helmet camera view. naturally that could cause some problems...
fov, camera shake and probably that movement also feel different on different viewing distances / screen size. imho the normal camera view, with helmet cam position and slightly lower fov (~ the normal camera from Shift, GTR and so on) and lower forward/backward motion (also longitudenal g-force usually have less unpredictably impact on handling then lateral, so it's no big loss imho) is the perfect compromise.