"What if your dive plan was to dive a wall to 100 fsw on air or EAN 32? Let's say a downdraft or a bladder malfunction dropped your buddy to 150 fsw. Potentially now there is a higher level of adrenaline, anxiety, as well as narcosis involved."
I am suprised that nobody said anything about this senario. MOD on EAN 32 at a 1.6 PPO2 is 132.
If you dropped down to 150ft on EAN 32, you would be recieving affects of Oxygen Toxicity, which a way larger problem than narcosis.
Basically Deep Air training, is really intended to go in hand with Advanced Nitrox. To really see the benefit of Advanced Nitrox, you start getting close to decompression, if not into decompression. Truly you really need depth to get into deco, yes yes i know that you actually don't, but if you add in the factor of your air supply you usually cant get into deco 100 ft or shallower.
Advanced Nitrox is the prerequiste for Trimix, why would you certify somebody with a new gas to go deep, without understand Oxygen to the fullest point?
This is atleast my understanding of why people take deep air course at the present timie. 15 years ago, the reason was probably completely different, at that time mixed gases wasn't the norm, so they probably taught the class to become aware of the affects of narcosis. Just my .02