I use the safest gas for any dive (subject to its availability), but continue to dive Deep-Air with OC. I'm reasonably familiar with my personal safe diving envelope. I now restrict my personal maximum depth on Air to 250 FSW. If Helium is available, I prefer to use it past 200 FSW, but it depends on the dive (I've selected it for lesser depths). That said, I've thumbed a dive using Air at 160 FSW because of how it effected my performance on that particular day. It really depends upon how I feel and the on-going performance assessment.
I might mention that most of my recreational Deep-Air usage has been before mixed-gas became more readily available. The bottom line for me is that using mix on a relatively shallow dive is a waste, unless it's needed. IGN varies considerably from one person to another. Whatever a Diver chooses to use on any particular dive is up to them. As an Instructor, I can conform to training protocols, make recommendations as to maximum depths and explain the reasons for a particular position, but once certified it comes down to the individual to make his/her own risk assessment.
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