It would be helpful to know the average depth at which some of these SAC rates were achieved otherwise a pointless measurement by itself.
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The whole point of calculating your SAC rate is to normalize it to the surface (remove the effect of depth). I have calculations for dives which have ranged from average depths of around 60 to average depths of 15. It doesn't make any difference. What makes a difference is water temperature and exertion level (and anxiety!)