Yea if you had that chain or docent on, a cocordant op and demon bracers on a Barbarian.. You'd be effectively increases your DR by quite a huge amount.
Could probably tank certain bosses while shield blocking and almost never needing a heal, even if they get through your DR.
On a Dwarf barb, the epic form could possibly be the best overall defensive armor available. Tho unless they have some form of healing amp on it, I dunno if I'd bother.
On a Warforged? Hmm, the docent of defiance would stil win I believe. Unless you needed the mobility the blademark will allow. (somewhere like VoN6 where you need to dodge the Dragonsbreath it could be quite nice)