There are lots of folks who will tell you that octopus breathing is safer, that buddy breathing leads to two deaths, but that's all speculation. You'll hear that all the agencies stopped teaching buddy breathing because people were dying in pairs because of it. That's simply not true. As hard as it is to believe, people are often irrational. Buddy breathing involves taking a regulator out of the mouth of someone you may not know very well (or at all) and putting it in your own mouth. While it cannot happen, people, being irrational, feared HIV transmission from buddy breathing. Before dropping the buddy breathing requirement, agencies sent out bulletins to their instructors explaining why HIV transmission could not occur via buddy breathing. They also sent out bulletings explaining how to disinfect second stages. The fear did not go away. I remember in early 1990, I had some referral students who were openly gay. My fellow instructors, who should've known better, expressed concern about buddy breathing and AIDS. Most agencies did not eliminate buddy breathing from their training, they made it optional. Some still allow it to be manditory in training if two second stages are strapped together so both divers don't use the same mouthpiece. These changes are the result of an irrational fear of AIDS.
Those of you who've received training in buddy breathing know that it is an amazingly easy skill. I can't imagine anyone not being able to do the skill correctly the first time. I've never stopped teaching it, in fact, I require a buddy breathing equipment exchange of my OW students. I've never had a student who didn't do the skill well on the first attempt. It's really, really easy. Fear of buddy breathing and statements about refusing to buddy with someone diving without an octopus are irrational. Hey, you have every right to be irrational, so knock yourself out.