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If you have been trained right, you know what your rock bottom reserve is based on real SAC rates and you don't need to rely on a rule-of-thumb like the 80/80 rule that is really just a line in the sand.
The 80/80 rule is similar to the end-your-dive with 500PSI rule often quoted. Both are simplistic rules for people too lazy or ignorant to take the effort to calculate their reserves properly.
The 80/80 rule ... like most rules of thumb ... is designed to be an easy-to-remember guideline for beginners, with the assumption being that as they progress in their education and experience they will develop an understanding of why those "rules" exist and when they are appropriate.
The best answer to the OP's question would be to learn something about gas management and then make your own ... informed ... decisions about what tank is appropriate for what depth.
... Bob (Grateful Diver)