Spoon:you can either go with the 5' or 6' hoses. the 7' hoses are for taller divers or divers who use a can light wherein they need the extra length to tuck under the light. i myself am 6' tall and tuck my hose in my waist strap and noticed that it would dislodge when i would turn my head at an extreme angle. got the 7' hose and problem solved even though though that their is a bit excess hose tucked in my waist strap.
but ask Shugar when he experienced an ooa and benefited tremendously with air sharing with me. beats having to share air while bumping against each other in the strong currents of bahura in anilao.
I have deployed the 6 ft hose in a real OOA situation and I feel that it need not be that long for open water OOA, well at least for my application. I think 40 would be just about right to run under the arm and up around the neck and yet be still comfortable as a donated piece thanks everyone.