I find no compelling reason for a 7' hose in OW with no overheads or Deco. Both my primary and my secondary are on 40" My secondary is on a rubber necklace around my neck and so can be removed by a quick pull.
Excluding a GUE or other experienced and tech trained diver who has had primary donate drilled into them, I believe that a true OOA diver will be an unpredictable beast. I will brief which ever method my buddy is trained with, but would always anticipate the unexpected. They can snatch whatever reg they want and it will be okay
I am set up to donate my primary which will be on a 7 foot long hose. My secondary is for me and I wear that in an "octo" necklace.
I feel that in an air-share situation, you need to have enough hose length to swim horizontally. This recreational 39 inch short hose is a huge compromise. Try swimming a length of the pool while air sharing and it wont be the most comfortable experience.
People think that long hose is for overheads but short hose appears to be a major safety compromise in open water.
I disagree. I have practiced both bringing a buddy up on my Alternate, and air sharing using my primary, both from 20m. When I say practiced, my instructors would have received Oscars for acting and didn't pull any punches for the assessments With a 40" I can bring us both up through a mid water in the ocean with currents Both my regs have swivels so they can be used side by side or face to face.
A calm diver is easy, I wouldn't want a panicking diver on a 7' I want them close where I can control them. I would be shooting a bag first and then maybe heading for the anchor line (but then in my location we always come up under a bag apart from very, very rare conditions where we drop an anchor
I happen to prefer my primary coming under my right arm and my secondary under my left. It gives me (and my buddy) options
You scenario is flawed the fact that a "safety stop" is not required. If you are in open water and lose air and your buddy has a 40" hose to share you simply go to the surface. You will not be doing "safety stops" when you are dealing with an OOA diver.
I disagree with this also (ish) If it's a true diver panicking, then sure, you're going to the surface, but you are "trying" to control the ascent. After all you don't want to be hauled up too quickly yourself. Certainly you want to get this diver to the surface and establish positive buoyancy.
However if you've gained control and calmed the diver, then there is no reason not to carry out the SS (assuming you have the gas)
I just ordered bp/w, 2 regulators and pressure gauge. I'm wondering how do you all run your primary and secondary regulators.
I would suggest for the moment following the set up you trained with - given you've ordered all new equipment, get used the the equipment with the standard configuration and then work out if you feel for your type of diving another method is best.
Getting used to a BPW and a strange hose configuration all at once maybe too much - 1 step at a time is my advice for what its worth