You do know the trick with that though: Steel 72s were made of a wonder steel that has never been duplicated. Talking about that with a friend, we were trying to figure out what was special about them. He said some tanks are just better than others, and we are just looking at the survivors, and thinking they all lasted long. I say they don't weigh much so they don't grind their glavanizing away as fast as say 100's.
When it comes to corrosion, I think it is fair to say I have more experience with it than other people. No one else thinks chrome regs die; I have worked at places that retired 5 or 6 per year due to corrosion. No one else has seen the square hole in old ScubaPro reg's inlet barrel corrode into a useless rounded off or notched shape; I use to retire four or five of those a year for just that problem.
Steel tanks lose their plating from abrasion just like any other material. And not surprisingly that abrasion is almost exclusively at the very bottom of the tank where the weight of the tank rests. (if you go no boot). If you have a boot, and there is a ring of corrosion "from trapping water", it's not from trapping water. It is the exact same sort of abrasion that comes from the weight of the tank resting on the very tip (in the unbooted tank case). It just comes down to this: do you want the wear concentrated at the very tip of the tank? or do you want the wear distributed in a ring around the bottoms of the sides of the tank? Concetrating the wear at one point will fail the galvanization at that point. Spreading the wear in a band will look bad but not cause failure.
Leaving a boot off will kill the tank, eventually. Leaving the boot on will kill the tank, eventually. Boot off will kill it faster because then the abrasion is concentrated on one particular point of the tank.
I am betting that no one who says boots off is good has had a tank fail due to corrosion, whether the boots are on or off. But in the tropics, steel tanks fail all the damn time. There is a reason why warm water tourist destinations use aluminum tanks. Tank failure is a race between the metal fatigue and corrosion. Steel tanks will win the metal fatigue battle, but still lose the tank failure war because corrosion will kill them, both internal and external. Personal tanks never see the abuse that rental tanks do, so steel looks durable. But I worked at a place that (for whatever reason) used 2640 steel tanks for rental, and they lasted about 5 years. More expensive up front, and did not last as long. Saved weight off the belt though.
