I never experienced anything wrong for lvl 80+ quests. But due to the massive exp needed to level up, you'll be probably doing quests, over and over and over and over.
I guess what you'll be asking is when you reach lvl 84? the quests are hunting the hairs of those yellow thingy (cant remember the name) and the crystals from miners. Take note that they are a very long drop so you would probably taking longer hours in burning rock.
The only disadvantage of BR quests is that you'll have to travel from BR to uruga which takes more than 3 to 5 mins or more. The only thing to remedy this is that those NPC in BR would be functional.
Another is that mobs in BR have high evasion, so you'll be spending more on stones than usual
