I ran Heroic OHB three times before the nerf, with the third group able to pull it off with just a couple of wipes. Oddly enough, it was after Thrall was released that I found the instance getting a bit easier. In my experience, it was the blasted lookouts with the short respawn timers that were the biggest problem.
Since regular OHB is my favorite instance, I was determined to finish it in Heroic. Once I succeeded, I swore the Heroic version of the instance off and have not even considered trying to do it again.
I would agree with Poldaran that once you are playing at this level, there are as good, if not better, chest pieces that can be had a bit easier. However, if you really want the mana-etched chest, I would recommend waiting until Heroic OHB is the daily and try to put together/get on a team in which all of the other members have not only been in Heroic OHB but have finished it as well.