Sure, nobody needs redundant computers on a single 30 meter dive, but if you don't have redundant time and depth information then aborting the dive is probably the right course. More important, if you are on a dive trip, only carry one computer, and it fails, then it's back to tables and you'll need to clear for 24 hours or more before you resume diving. Same deal even if you have a spare computer that lives in your cabin.
I was talking about a 30 foot dive, not 30 meters, and I didn't recommend aborting a dive, I simply said I could make good decisions. I've never had a computer fail on a dive trip, though I've seen it, and I've always had access to a spare if a failure did occur. I don't think waiting 24 hours is an unreasonable penalty for such an event considering how unlikely it is in my experience.
The reason for choosing my example was experience. I did a trip where I experienced the "sync before every dive" feature that resulted in most every dive happening without an SPG. I simply stayed shallow. On one dive I was treated to an empty tank as well so I ran out at 15 feet 40 minutes in. With modern regulators you get ample warning and it's no big deal.
Actually, it was George himself who said that. Of course, their team has videographers who clearly violate DIR doctrine so George is not only arrogant, he's a hypocrite. ;-)(and I also agree with Craig that "a DIR photographer" (like a photographer dive buddy) "is an oxymoron")
I find open water divers that breath a long hose and wear a necklace as amusing as you find photographers that use Air2's. An Air2 will not accumulate scum, it will get operated on every dive and it will get serviced, thus insuring that the inflator itself is serviced rather than neglected. It *also* eliminates a hose and I always know where it is because I'm constantly using it. There is no reason to disparage the use of an Air2.I do use happily wear my my spare 2nd on a necklace instead of a scum-ball.
The needs of a full caver diver, of which I am certified, do not translate fully to open water and given that the priorities differ, gear decisions may as well. That is truly "Doing It Right".