I'd like to know people's thoughts on the use of helium to mitigate the effects of narcosis and whether or not this is a "weakness" in a diver. I'd also like to know what alternative would be suggested.
OK, I'll play. My thoughts..
Saying there's a "weakness" in a diver that chooses to use helium is stupid -- it leads to a herd mentality that can be dangerous -- "What, are you a chicken?" You should never call someone weak for wanting to mitigate risks.
As for my thoughts on using helium to minimize the effects of narcosis, and my personal decisions, I will say "it depends on the dive plan, my dive team, the site conditions, and the risk I'm willing to take." I need to also add that I have a fair bit of deep air diving background, to depths shallower than "completely stupid" but definitely deeper than "he's a moron."
Back in the stone ages, we used to switch to air at 190' when coming up from deeper trimix dives. For many reasons, I wouldn't even begin to consider coming off a helium mix to air at 190' now, and would stay on trimix to around 90'. So for deeper trimix dives, I'm using helium deeper than 90'.
Warm clear Caribbean diving where I'm just screwing around and all I have to do is go up in the event of an emergency, I probably wouldn't blink at a dive plan sans helium to a depth of 170-180'. I might have even done a dive or two in that range on air this past summer in Belize.
Cold, dark, site? I'm probably using helium below 100', and definitely below 120'.
Cave? Probably using helium below 120'. Definitely using it below 140'.
So.. It depends.