The problem with most of these replies is no one is stating what type of gear they are wearing to tank and heal as Ret. Not everyone has T6, T5, or even T4.
I am in mostly Northrend stuff now. I think it would a little iffy to tank as Ret in just the stuff you have received from quests and drops in Northrend. Of course it all depends on your healer and dpsers skill and gear too.