I kept editing as i thought of more to say, but i know very little more than you on this subject, and most of that was due to reading on here and talking with my instructor. Now you know all that i do, so consider it equal!! They dont cover all these other valve types beyond the yoke/K and partially the DIN and J valves. The book/CD suggests that you shouldnt use the J and i believe it gives the most emphasis to the yoke/K due to its popularity with OW divers, and particularly to rental gear that OW students use during their courses.
