Several years ago we had a fatal accident in the gulf of Finland where the victim's octo was in one of those "pacifier" looking holder cups that completely covers the mouthpiece. The victim had ripped the octohold free from its clip, but the cover was in place. The investigation concluded that her failure to get the cover off the mouthpiece, i.e. the poor accessability of her alternate air source was likely to have contributed to the severity of the accident.
Briefly: not good, too difficult to use in a hurry/high stress.
---------- Post added December 17th, 2014 at 01:05 PM ----------
I would strongly recommend the necklace. In all fairness your greatest concern is for yourself and you could not possibly find that extra reg more quickly or more easily than when it is on a necklace around your neck.
I don't like folding the hose through. D-ring because I like to have the rings available for other items and I suspect it isn't great for the durability of the hose.
Briefly: not good, too difficult to use in a hurry/high stress.
---------- Post added December 17th, 2014 at 01:05 PM ----------
I would strongly recommend the necklace. In all fairness your greatest concern is for yourself and you could not possibly find that extra reg more quickly or more easily than when it is on a necklace around your neck.
I don't like folding the hose through. D-ring because I like to have the rings available for other items and I suspect it isn't great for the durability of the hose.