Right. The way I want to implement a computer is plan my dive using my v-planner desktop software to see how long I'm thinking of staying and how long I can stay while maintaining proper gas planning. Have tables in pocket with bottom timer on wrist, but use them as backup. I'm going to ride the computer as my primary means to decompression after planning out how long I can stay and familiarizing myself with different profiles.
A computer is a very expensive "back-up" device to tables, especially when it can't compute lost gas, which is one very good reason to need a contingency plan that actually does happen. So the Cochran is not really backing up much, IMHO, other than I stayed X minutes longer/shorter, or X feet deeper/shallower. Shame, it looks like an OK unit besides that.
It's a philosophical issue, but my opinion is that riding the computer is already half way to a chamber ride.
If I plan the dive and dive the plan I have no need for anything other than the tables and bottom timer and more importantly I know exactly how many stops I have, the first stop depth, how much time I have at each stop and my total ascent time - and I know I have figured my gas planning on exactly that information and will consequently be fat on gas with at least a 1/3rd reserve as long as I start the ascent at or above X pressure.
You have no idea how far that goes to de-stress a dive. With a computer, you have to use a software planning function (which the Cochran Analyst Pro software has) in order to know where you will be in terms of first stop, stop times and total ascent time. And once you are in the water, the computer tracks things differently based on the acutal dive, not max depth and time parameters and the numbers it finally gives may differ significantly from what you planned - creating stress as your computer demands you do something that varies from the gas plan.
If your computer does not use exactly the same deco model as your planning software or table, you start out with an even larger variance between gas plan and the actual deco.
So while it sounds strange to use the computer as backup, it is a lot more comforting for divers who like to know exactly how things are progressing and exactly how the dive will unfold.
And in the event you do have a lost gas issue, the only change needed is to flip to the right page on the wrist slate or in the wet notes and ascend using the contingency deco for loss of either deco gas or your single deco gas. Again,this results in a much smoother transition than messing with the computer to select a new deco gas, resulting in less immediate stress. More importantly, with the computer and the new gas parameters, you will not know exactly what profile it will provide, creating more long term stress about whether you can safely finish the dive.
Now if the computer and tables or your planning software match very well and/or if you plan all the lost gas contingencies on the computer's planning software you can get to the same level of confidence with your computer - but you still need to put the deco schedule and contingencies on a slate in the event the computer fails - so to do it right with a computer as your primary involves about twice the pre-planning work. Consequently, due to the higher work load the diver gets complacent then gets sloppy, then gets hurt when the unexpected happens.
So again, my feeling is that the ideal role for a computer on any dive with significant deco is as a backup to your tables or PC sioftware generated plan in order to get you to the surface quicker if you abort in the middle of the dive due to an emergency. I won't know the exact profile on the way up, but I do know it will be much shorter than the profile I planned ensuring loads of excess gas.
