Gassy, Old Chap,
I am of the generation that first saw computers that took up whole rooms, ran with vacuum tubes, and could add two and two almost as fast as a human... So if there is a generation that should be circumspect about them, it is mine.
That said, I think that you will agree that substantial progress has been made in their reliability, etc. In fact, your daily life--from the use of cars, phones, coffee makers, pcs(!)--has been dramatically affected, if not improved, by their presence. I think that they have made diving so much more enjoyable because they have freed me from "slavish calculations" every time I dive.
That said, I am aware of the "rough" time/depth/SI limits on any dive. So, after a 100 ft dive for 25 min, I would not believe my computer if it said that I could do a 60 ft dive for 40 min after a 20 min SI! Also, if it went dead 10 min into a dive I could ascend gracefully at that time with no threat to my life. Etc., etc. Thus, I think of the computer as my primary and am willing to give up diving for 24 hrs should it die on me mid-dive. BECAUSE THAT IS AN EVENT THAT WILL NOT HAPPEN VERY OFTEN. AND THE DEATH OF A COMPUTER MID-DIVE IS, OF ITSELF, NOT LIFE THREATENING TO THE HUMAN CARRYING IT.
My message--maybe lost in all that verbage--is that modern computers are sufficiently reliable to use as a primary if used intelligently. (Of course, you could question my intelligence--and you would not be the first!).
Joewr