Inverted doubles seem to be fairly popular in the UK.
(because there are lots of commercial divers who are also recreational divers).
it puts the valves where they are most likely to suffer impacts when tanks are moved around.
Agreed - I've seen custom guards that protect valves.
Maybe Tobin could apply his wizardry? Many (most?) rebreathers are valves-down. I used to have a set of Divators (valves-down), but getting 4,500 psi fills became too inconvenient.
I agree with ALL the prior posts about stretching and fitness. But I don't like depending on both my body and all my gear working anywhere close to 100% to ensure safety. I like
BIG FAT margins of safety that accommodate sloppy real-world variables. Mix in the unpredictable conditions of San Miguel/Santa Barbara/San Nic/San Clemente islands + possible gear failures + possible entanglement with monofilament high-test line. Then what? Fatter margins means not running out of options.
The commercial aviation industry figured this out decades ago. Without passengers, flight crews are allowed to ferry airliners vast distances to get to a repair facility with MANY systems in "failure" mode. A cadre of underwriter-approved "gear-head" pilots are hired for these ferry flights, for their expertise in managing and not aggravating problems en-route. Point of the story? Why should the recreational dive industry promulgate thin safety margins for a risky activity? In my opinion the "right" dry suit or underwear shouldn't be how you close a safety gap that's bound to catch others who are not 100% vigilant. The status quo only benefits those concerned with maximizing profits ("
diving is as safe as bowling") by cutting costs and capping liability exposure with lowest common denominator standards. That said, warm-water diving doubles in 3 mm with healthy shoulders? Absolutely go valves up.
Side mounts make sense in some scenarios, but not for SoCal kelp divers who need unencumbered arm movement for spearfishing or manipulating camera housings / strobes - all while dealing with surge.
Unquestionably, valves-down is somewhat less convenient above-water for dive professionals who provide services to dive consumers. If moving tanks above water becomes a bit more burdensome, or a boat's tank-rack / seats need minor carpentry, isn't that a small tradeoff vs. making diving safer?
AndyNZ's comments are well reasoned, and illuminates how it takes the momentum of multiple people deciding, separately, that the pain of the status quo is worse than the pain of navigating the change - then lots of people can share their spare parts and know how hoses are routed.