I started using DIN in the early 70's (with used Poseidon tanks I bought in Puerto Rico). It wasn't even known as DIN back then. In the US, I don't know of anyone that was using DIN connections back then.
I don't use DIN much anymore. I prefer yoke connections. They are easier to use, very reliable and much more forgiving in a harsh environment.
In the long run yoke is much more durable. The chrome on the female DIN threads wear too easily and then it can damage your threads on regulator.
In a corrosive salt and sand environment, yoke is a much better connection in the long run.
I talked to a dive operator (in the Philippines) that offered DIN valves (she was a German lady) and she said DIN is great: "We just have to replace the valves every few years, valves are not that expensive anymore". I guess that is a work-around, but it just points out that they are delicate. You just hope that it is not your regulator the last one connected before they need to replace the valve.
I have had to use a wrench a few times to disconnect a DIN connection after a dive. Some very small grit just got in the threads during the connecting process and locked the threads when I pressurized the connection. At the end of the dive I completely purged the connection, but could not take it apart without a wrench.
DIN valves not only receive a lot of wear in the threads, but they are also very easy to deformed if dropped or banged. In Bonaire were shore diving is common and you take the tanks in the back of your rental pick-up truck with you, tank valves receive a lot of abuse. I was talking to our dive operator and he said that he would never offer DIN or DIN convertible valves. "Divers are not careful and they drop the tanks from the tail gate way too often when they are setting them up." Only a yoke valve can survive that kind of abuse. Sometimes they get damaged, but more often than not, they are still usable.
Both DIN and yoke connections are secure connections when properly mated. DIN has the advantage of having a lower profile without the yoke screw. But I personally find the yoke screw more continent to work with. DIN is very secured when matted, but the two components when are not mated are relatively delicate and exposed to damage.
Yoke connection is also used on portable O2 cylinders and other industrial gases. It has proven to be a very robust long term connection for a very long time. Most (if not all) the issues that I have heard about yoke connection can be normally traced to operator error or damaged hardware. It is more difficult to damage the hardware on a yoke connection that on a DIN connection, but it can still happen.
