Why not?slonda828 wrote: You could figure out a way to use a double hose with a long hose...but why? Why point does it serve? If you are in some crazy cave, then a doublehose isn't the best choice.
I agree that for my alternate regulator or decompression gas / stage cylinder regulators, a single hose is by far the better choice. But my regulator of choice as my primary regulator for any extended range or overhead environment (AKA technical diving) is a double hose regulator.
I used a DH regulator as my primary regulator for my technical diving classes.
For any extended decompression diving I also used a Phoenix RAM as my primary and a Conshelf (1st stage)/ Scubapro 109 (2nd) combination for decompression gases including O2 stage. The same thing for ice diving and wreck diving.
The only time I can see a Dh being somewhat inconvenient is if I am traveling and I need to borrow or rent a set of modern doubles with outlets on the on the side. But, I have already been thinking of ways to use my DH in that situation. IIRC, the Cousteau team used triples with the regulator to the side when they did the Britannic.
I am not a cave diver and have no interest on doing any Florida caves, but if (or when) I do some Cenotes in Mexico it will probably be with an Argonaut HPR double hose regulator.