As you said, it is something that can easily be discussed beforehand. I hit 60 on my PLD about 3 days ago, but having already levelled two others to 60 before it meant I had a good idea of what I was in for along the journey. Getting to places like Vault at 57 was the point where I'd simply wait at the start while everyone is shielding and say 'hey, look, I know this dungeon hits hard and I know my shiny Titanium gear won't be optimal for pulling massive packs so, you know, deal with it' (in less, usually more polite words). 9/10 chance is you'll get an "Ok" and everything proceeds as normal, except everyone now knows what to expect rather than just charging headfirst and testing the acid-bath.
Meanwhile, I still get BWall Expert Roulette runs with tanks pulling all three first packs and getting the group killed with DoT's while the Healer is strained trying to keep the tank alive and unable to cast a single Esuna. No communication, nobody knows what to expect, just 'CHARGE', /splat, followed by the inevitable "It's healers fault... Wait, no, it's the tanks fault... Hermagurd".