Ditto here.Thalassamania:By and large I use NITROX in place of air, when depth appropriate, on air tables (or an air computer). I take my margin in the extra risk reduction rather than in longer bottom time or shorter surface intervals. On one dive I notice little or no difference but on a multi-dive, multi-day series of dives I feel that I have much less fatigue.
I dive on Nitrox tables if everyone is on the same Nitrox mix, but most of the time at least one other diver dives on air - which leaves me diving air profiles instead.
I don't notice any change after only one dive, but on repetitive dives it makes a difference. How can it not? You do absorb less nitrogen. I doubt this positive effect on fatigue could ever be scientifically measurable with enough accuracy to be proven beyond any doubt.