I do agree with you that there have been no solid findings however even a placebo can have positive effects. My thought process is that as long as the Nitrox is not doing you any harm, and you are not trying to sell it based on said speculation, then it is great if a person BELIEVES that they feel less tired after a Nitrox dives.
This is a purely non-medical or scietific opinion, but every once in a while a placebo can be a good thing.
While I agree with you on the placebo effect, I don't think it is a placebo effect. I think it is very real.
I am just cautioning everyone that no study has been done on this, and there is no known physiological explanation as to why this would be true. The fact that no study has shown it, and there is no such physiological explanation does not mean it is not true. It does not mean anything either way. It awaits further scientific investigation.