I’m a FFM instructor, and I think you over-emphasize the theoretical "gasp" response of water touching a diver’s face To the point of possibly scaring people away from the benefits of a FFM. A full face mask is a different piece of equipment than most divers are used to, but it’s not a hazardous, technical apparatus. If the student has completed their open water course to standard, they’ve felt the rush of water over their face when they removed their standard mask both in confined and open water. To me, it feels no different Even under the ice.
Otherwise, this is a good, informative write-up about the unique challenges of FFM diving. I would just caveat that it’s a challenge, and only a hazard in the theoretical sense. :)