rstofer
Contributor
Probably depends on the person. Some would rather save the money and do some simple algebra. Others would rather spend the money and not do the simple algebra.
That said, I've yet to see a gas integrated computer that will signal to ascend before your buddy is too low on gas to get you to the surface.
But it's getting closer! There are now air integrated dive computers that will at least monitor multiple divers (up to 3 I think). I don't know that they do Remaining Dive Time calculations for other than the primary diver. They certainly could.
Before I ever started my Open Water I class, I had already formulated two principles for safe diving: a) I didn't belong in the ocean, everything was foreign and b) if I ran out of air I would die. Pretty simple concepts. My NAUI course dealt with the details of air consumption at depth and they were adequately demonstrated during my training.
But I didn't really need the class to remind me of my first two principles. So, I have always watched my SPG like a hawk. It is the only thing that keeps me from violating my 2d principle. I also tend to watch my buddy's SPG. A little paranoia will go a long way toward increased safety in this hobby.
Richard