We are currently using the Orfit AIO Solution for immobilization of all our patients including our H&N patients.
At our primary sites our standard H&N are just done with standard Orfit 5 point H&N masks. Patients with previous treatment (i.e. matching to previous RT field doses) or getting SBRT infield boosts get the open face H&N masks and the AlignRT system is used much in the same way as any of our intracranial SRS cases. There isn’t a mask on the market (warning this is only my opinion) that facilitates a "rational" use of Vision RT for H&N that I am aware of (I have played with modifications to our current masks but nothing extensive). Just an open face ROI doesn’t ensure neck and shoulder positioning is correct in a sub-optimal 5 point open face mask based on the data I collected so alternate ROIs are required.
In our experience a well made 5 point H&N mask (open face or standard) the shifts are very small using a standard "marks on mask" type of setup so they are equivalent in this manner. If you use the open face ROI for setup and compare those setups to the "marks on mask" setups of the same patient there are very small differences with the ROI setup being marginally better (meaning smaller residual shifts after CBCT). I could find no benefit of the open face mask setups relating to preventing interfraction neck and shoulder discrepancies (for patients undergoing weight loss for example).
Using only an open face standard head mask (3 point whole brain style) and leaving the shoulders open for monitoring via a secondary ROI has shown to be problematic (at least in the iterations I have attempted). It isn't that it can't be done because it is done at some sites. I just don't see the benefit in the additional monitoring and setup time over a good (read "well made") H&N mask.
As far as patient comfort goes the open face masks are by far and away a preferred option by the patients