To date I have worn this through all of the 25 man boss content with out issue. Of course I am not main tanking Sarth +3 drakes (we are at +1 now working on +2).
I will replace with the Harvester helm if I ever see it, (Vital Protection). I may also grab a EH helm for the big U when that hits - but I have had no issues with content to date using the enginering helm. I love the massive Defense and expertise on it.
"It takes less time to properly mark, CC and pull then it does to run back from the graveyard".