I have personally experienced being on the donor end of out of air emergencies twice. Both OOA divers were not my buddies. In both situations they grabbed my primary reg and I had to put my back up reg (octopus) in my mouth.

The first incident was on a wreck in 70' of water. The diver just yanked my regulator from my mouth, and started giving me a frantic thumbs up signal. I tried to calm him down and was able to get him to the surface at a decent ascent rate.

The second incident was a little calmer. I was on a dive with a camera and the OOA diver came to me and gave me the signal, before I could deploy my octpus, he yanked my primary.

Based on my personal experience, I always warn my students that there is a 50/50 chance that the person who OOA will yank your primary.

In technical/overhead enrironment I dive with the long hose on my primary because I will not take the chance that the person who is OOA will not hae the long hose and cause a very difficult exit if we are in a cramped space.

I took my DIR F before my Cave classes. I took my cave class from a NSS/CDs instructor because there were no GUE instructors availabel during the time. I finished my full cave with a NSS/CDS-NACD Instrucor. They both strongly advocated and taught the primary was on the long hose.

The breathing a long hose on the primary is not and never will be an exclusive of GUE. It is well thought of skill thatis taught because of personal experiences like mine.

Jim