So you calmly shut off the tank valve, retrieved your 2nd stage, screwed it back on, repressurized it, tested it, went back to your desired 2nd stage, then continued with you exercise.
SM rules!
I think what you meant to say is "redundancy rules".. right?
I mean, I'm assuming that you feel the same way about backmounted doubles. Although it's not quite the same thing. With manifolded BM doubles, no matter what happens to that regulator - whether you drop the second stage off a wall or blow an LP hose - you still have all of your gas!