[IanDennis]

Irrespective of whether your DIR or not, then DIN offers a number of advantages over A Clamp. By using a captured O ring system and screw in valve then the DIN – Deutche International Norm -offers much greater security and are less likely to become unseated. 300Bar Din threads can be used in 232 bar cylinders and provide a high level of security for the valve. When the Din regulator is screwed into a DIN valve it creates a gastight seal between the cylinder and the regulator and whilst it is possible that if the regulator is depressurised that the diver could loosen the regulator to tank connection this is highly unlikely in normal diving.

A clamps have been around for a long time but in a technical environment that may be considered unsuitable due to the potential for them to become unseated from their position on the cylinder valve.

If you look through books such as

An introduction to Technical Diving- Rob Palmer
The Technical Diving Handbook – Gary Gentile
Doing it Right- the fundamentals of Better Diving – Jarrod Jablonski
IANTD technical Diving Encylopedia – Tom Mount

Then all suggest that DIN regulators are more appropriate for technical diving.

I do not believe that the GUE site states whether AClamp or DIN should be used but for the reasons above DIN may be a better choice for more adverse environments.