Buddies
This is really the big one for me.
Some stuff that DIR/GUE does makes sense to me and I have adopted it (BPW, primary donate, necklaced backup reg).
Some stuff (must be a light with a certain kind of handle and we are going to communicate via light signals) makes sense in the context of what they are doing, i.e. cave diving.
Some things (drysuits and doubles for most dives, helium past 100', etc) are either overly cautious or just not relevant to my world, and that's OK.
The one I absolutely cannot get on board with is team diving. To me, diving has always and will always be a solo activity. Yeah, I might go dive with someone else, but I expect them to be 100% responsibile for their own safety and likewise do not include them in my own contingency planning. If we get seperated then I'll see you back on the boat. Spending half my tile trying to keepntrack of another diver in water with 5' visibility is not my idea of fun, and I am doing this to have fun.
Generally, all this would fall under the category of "Dive and let dive". To me, GUE/DIR is kind of like the hardcore vintage divers. Cool, you are doing something different and a bit strange from my perspective, but hey, more power to you. The difference is that I have never had a vintage diver claim that theirs is the only proper way to dive or tell someone that using modern gear will kill them, or, despute having never met someone, that their buoyencynand trim are not good enough. I don't care if you are perfect, that attitude only breeds resentment from the rest of us who are perfectly happy just being good enough to pursue the hobbynwe enjoy.