I've been testing, with the 0.9.0d/e hotfix nerfing Firebrand it struggles in early empowerd monos in the endgame without perfect rolls on gear, but can still manage otherwise. I think the damage potential now is a little lower with the changes to crit on consume of stacks for Flame Reave, but with an Opulent Focus as offhand (instead of dual-wielding) it becomes much more survivable, which offsets the hit to damage when swapping the offhand instead of a second weapon. Basically, it can't 1-2 hit bosses with Flame Reave anymore, but with slight tweaks can sustain through and still does tons of damage.