If you play a big hp, no AC class like a barbo, you should probably farm for some decent healing amp gear (which is way easier to gather than AC gear): leviks, tod ring with proper augmentation, DT armor rune, epic gloves of the claw, etc. That will enable you to play main tank on epics or ToD if no other choice is available, while at the same time won't have you wandering off your desired path, build or playstyle most of the time. If you are not tanking, however, you might as well take off your healing amp gear and put on your DPS set because, as it has been said before, chances are you will end up being overhealed.
For tank builds, the story is IMHO different. For a tanking-oriented build, healing amp is like living very close to a hospital. No doubt it can help you stay alive, but it's not the same than being healthy.
For non-epic content, my priorities -for a tank- stand like this: AC, hp, saves/DR, and healing amp. Being hit 1 out of 20 times is too good to ignore, provided your build can hit that milestone -and- you have enough hp to endure that roll of 1 against disintegrate.
This doesn't mean AC tanks shouldn't farm for healing amp because on epics AC is -sadly- of little use.