Here is my armory and I should be in tanking gear

http://www.wowarmory.com/character-sheet.xml?r=Frostwolf&n=Obamantwan

I have recently upgraded my neck, weapon and ring. HOwever, I'm wondering if my current gear choices are in fact better than what i had on previously?

The only pro i see of using the Slayer of the Lifeless as opposed to the Red Sword of Courage is the added strength... In fact I believe my total avoidance is even lower with the SotL... Definitive upgrade? please debate.

THe neck i'm pretty sure is a clear upgrade but just to compare, I'm debating neck from malygos and the badge of heroism neck in this slot...

LAstly, i'm questioning whether or not I should craft the epic tanking ring from Jewelcrafting, to replace the Heroic Gundrak ring. Any thoughts on this?

I'm trying to optimize as best I can so if u see any other slot/enchant that I should look at doing differently, please inform me. Thank you.