I completed the quest in 490 gear and used green fire all the way up until just a few days ago. I switched primarily because, while I used to get whispers everyday regarding the quest (either how to get or advice on how to complete), I never do anymore. The quest has become too easy.
On a secondary, less important, note: The new dreadsteed is truly abysmal looking. I did the original dreadsteed quest at 60 and I am a very proud warlock, the 5.4 update for a green dreadsteed was a huge mistake imo.