I have an open face helmet - but then I sit on the 'wrong' side of the car and don't have a steering wheel in front of me. I also find it easier to talk to marshals at time controls with the open face helmet. The downside as people have already mentioned is getting insects in the face - our roof vent scoops them up nicely and fires them into the car. At least since putting a finer mesh over the vent they come into the car in smaller pieces
