No, I am not the paladin in question. I play retri and some days ago I joined a raid with a prot pala in it. We killed first boss in ToT and the plate dps chest dropped. Prot tank rolled need on it, saying it is BiS slot prot pala until heroic mode. He explained it's the huge amount of mastery on it that makes it good. It's not that he is a ninja looter, he truly believes dps gear is BIS for tanks. I talked to his friends about it and they agreed with what he said.
Is he right? Are prot palas supposed to equip some plate dps? Is mastery so good for prot pala they can forsake other tanking stats and stamina?