From downloading peoples profiles on our rentals, and helping customers with their stuff after they come back from a trip, my experience will disagree with your statement a bit. Over all, computer users end up with about half again more bottom time based on the fact that it is taking into account shallower parts of the dive when you are not loading nitrogen as fast. I have a bunch of 100' max depth for an hour and 10 mintues in my log book... don't think I could have done that on tables... would have been over in about 15 minutes, so in my opinion, yes, you will get a lot more time with a computer, unless you are diving an exact square profile, and unless you are welding on a pipe at 60 feet, then coming straight up after 40 minutes.... you probably will never dive a square profile in your life.