Setting up your DC to reflect what you are actually breathing doesn't mean you have to give up anything - just don't stay down until you are at zero NDL (same is true on air). Setting the mix you are actually breathing also gives you an accurate picture of where you are at all points of the dive (NDL and MOD). However, to each their own and if you want to dive an air profile on Nitrox, so be it.It's low-risk until it happens to you. (No, I've never personally been bent.) But by running your computer o the exact %, and then squeezing out every single minute you can, puts an awful lot of faith that the algorithm in the computer exactly/closely matches your body physiology and I personally think that's an unacceptable risk. I'll willingly give up 10 minutes of bottom time for a little extra margin.
- Ken