Hi
@dhaines429
Last summer I bought a second single tank setup, mainly for travel. I set it up with a 40" primary with an omniswivel running under my right arm and a 22" second on a necklace around my neck. I have found that it causes more jaw fatigue when diving 3-5 hours per day than my old setup with a standard primary. I think it is just the weight of the regulator and hose pulling slightly right and down.
@tbone1004 states he does not have this problem with a long hose. I will probably try a 5 and 7 foot hose for myself. My 1st is a SP MK25, I'm also going to try the 5th, downward pointing LP port for the primary hose, to see if that helps.