I asked a question vicariously in w00ters, and Mod Mark responded.
"I find brink far easier than before tbh, use better abilities and different gear".
So, erm, looks like I need level 80 weapons then. Fine. 80 ranged shouldn't be too hard, and then I just need to work out killing QBD. Still, he should know that polypore/godsword/hand cannon won't do it, and they're the level 75 ones. I definitely can't afford level 80 armour, so I'll be sticking with what I have on that front. Brink of Extinction is nonetheless a rather hard quest, especially when you face more than one combat triangle side at once and can't realistically use melee.