I recommend you jump into the main story ASAP and get it done before Heavensward hits as the area of Ishgard will not be available till after the current storyline.

As for nerfs - one story line fight was nerfed, you'll see it later. And Final Coil of Bahamut has received some Power of the Echo buffs, but no nerfs.
The Golden Saucer gives more MGP and the Poetry weekly cap was raised from 450 to 900/week.