Tanking Tier 5 content is not much different from tanking Tier 4 content; bosses hit a little harder, and strategies are a little more complex but not so much that it takes too much thinking to complete the encounter. I got my first taste with The Lurker Below just before Christmas, followed by Void Reaver, more recently downing High Astromancer Solarion, and currently working on Hydross the Unstable this week. Progress is coming fast and furious now and I even picked up Tier 5 shoulders, Crystalforge Shoulderguards not really an upgrade to what I have but they give me some versatility with my gear.