Interesting thread, as are most in the Rotorheads forum.
Story:
On one of several visits to the dunker, I was sampling the variety of seats. Strapped in the back of a "Lynx" with the seat athwartships, I felt that the egress would be simple... right up to the point that I tried to release my harness. I had a lungfull of air, I had a reference point, I had divers close by, but the stress that set in immediately was overpowering. I tried as hard as I could to rip this harness buckle open but it was not going to unlock. Panic... you bet I did.
A friendly diver who was behind me reached over, calmed me down, and tried to open the buckle. Not a chance, this thing had locked and was not going to play the game. We were now at about 30 seconds in the water and I was fighting the desire to breath in.
The diver calmly reached for the harness anchor point and unclipped the whole thing, releasing me from the seat and allowing me to surface.
The point that was forced home to me, was that, even under controlled circumstances, panic, disorientation, stress and a bit more panic, set in very quickly. I could easily have unclipped the harness at the anchor point, but I didn't have the presence of mind. I can only imagine how difficult the exercise would have been if I had just autorotated to ditch, with parts still splashing around me, and possibly with an injury and a passenger to take care of.
Bottom line for me... if I am flying a single-engine helicopter without floats, I fly around anything bigger than a puddle.