MikeFerrara:It only becomes dangerous when we have divers who are too unconfortable and not able to control their position well enough to impliment it...in other words, the other holes in entry level training are what makes buddy breathing difficult.
I don't think buddy breathing in and of itself is stressful, but without a mask I found it somewhat stressful. You have lost your source of breathing and the ability to see your buddy clearly who has control of the regulator. You have to have complete trust in your buddy, particularly when the regulator is attached to his or her tank.
It seems to me that for buddy breathing to work well, there has a be a large degree of trust in the buddy. I see people with such poor buddy skills I have to wonder if they could manage it without someone getting hurt. It is also something that needs to be practiced. Most people don't even practice sharing air with an alternate. I think there is a larger cushion for error in sharing with an alternate as opposed to buddy breathing.
To me, it is not a matter of skill per se, but a matter of trust. I can do an OOA drill with my buddy on descent and confirm that his alternate is working. How can you ascertain how well your buddy will react in an emergency?