I guess I'm in the minority here; I'm going to say that the long hose is a minor nuisance. Can you make it work? Sure, but it's one more thing to keep track of, one more loose end. I have a long hose on my twinset regs but on single cylinder dives I use a 40" hose routed under my arm with an elbow at the 2nd stage. I think that's sufficient for any dive that doesn't involve a cave or penetration.
I'll agree with you.
Personally I believe that 40" is long enough in open water (both my hoses are 40" on swivels, and my Alt comes under my left arm). While I've never donated to an OOA, I have had to air share a few times while guiding someone who has been heavy on their air.
For
me a 40" hose diving in the ocean, it's perfect, as it's long enough to have some space, while it's short enough to be able to maintain control of the diver. Especially when you encounter strong currents, you certainly don't want a large separation. It's also easy to manage if removing kit in the water and passing it up, especially on vacation dives. It's just easier on the crew etc.
I get that some people like to familiarise themselves and dive with one set up, I personally don't find that an issue. My BCD for training has a conventional rig, my SM though has 2 long hoses. As soon as I strap on that particular rig I automatically know where my Alt reg is without thinking or fumbling about.
Finally: when I've been teaching rescue class, I've had a small number of people turn up in BP/W and Long hose. No problem with that, but on each occasion when under "stress" their OOA donation technique has been a shambles. More than once I (as the panicked diver) had been able to attach myself to their bungeed second (Alt).
I have no problem with people's choices of equipment configurations, I just wish though rather than adopting a practice because they've read or heard about it, they would think the configuration through. In my opinion there isn't one single configuration that is optimised for
all different diving environments. Each has it's own pro's and cons.
Before adopting a particular config one should assess it's suitability for your kind of diving and situation. For me the downsides of the long hose (in open water) far outweigh the positives - which are applicable to an extremely rare event.