How can anybody become a "thinking diver" if they are not allowed to ask for evidence of claims?
If you're relying entirely on external scientific validation, you're not really thinking for yourself, though, and you're dealing with decompression research which is a scientific field of study for which there are considerable uncertainties. So every time you do a decompression dive you have to find some way of distilling all the information that you have and turning that into a decompression schedule that you are going to follow.
Myself, on the one hand, I've know that people used to be scared of helium. I know there's a lot of fear over "helium bends". On the other side there's GI3 ranting about helium weenie factors in deco programs and that nitrogen is what'll bend the snot out of you. I know there's the more solid science that BRW discusses in that passage that was quoted, but translating that paragraph into practical decompression profiles is difficult. There's also a training agency that dives helium mix like nitrogen, only with mandatory deep stops. I know that I, myself, tend to feel better with helium and worse with nitrogen the way that I dive. I also know of a case of a diver bent on 21% in a mixed team with 21/35 divers and another case of a diver blowing off shallow stops on 21/35 who walked away fine.
Rational people may come to different conclusions given all that. I tend towards thinking that helium is better than nitrogen provided that you do your deep stops and don't pop (blow off the shallow if you must). Other people may discount GI3 (easy), discount the experience of GUE divers as having all the same flaws as experimental medicine, discount the two deco examples I've got as low-N, and discount my own experiences as being subjective. There's *no* good experimental evidence, however, either way.
So as a technical diver you need to pick: Team Helium or Team Nitrogen. Science will not answer the question for you, it is inherently uncertain. You must, in fact, become a thinking diver and listen to what your dives are telling you.
