I don't necklace either. I have long hose on the right bottle because it allows for more streamlined OOA situations. No regulators crossing sides, if diving with a diver in backmount they will be used to the reg coming from their right so having the right bottle with standard regulator orientation makes it easy that way. Left bottle has reversed 2nd stage with no hoses behind my head. In an OOA situation I donate whatever regulator is in my mouth, following the standard reason for donating your primary, you know that reg is currently working and is already cleared so no reason to purge or worry that something isn't working. You switch to the other 2nd stage and after everyone is happy after a few breaths, you switch regulators so the OOA diver has the long hose. Pull long hose out of retainers, and out you go. It is the way that makes sense to me in my head and to me that is all that matters. Regardless of which side you choose to put the long hose on, the OOA diver should always get the regulator in your mouth and then you swap after everything calms down. If you're a neck crosser, then a necklace may make sense and long hose would likely end up on left bottle. Beauty of this style of diving, everyone has their own opinions and most of us are open to changed and aren't in paradigm paralysis