I prefer 20 defense to shield. I do have Titanium Plating on my The Skull of Ruin - Item - World of Warcraft, but I only really use that when soloing.
What is a better option for a prot warrior? If you are an OT and doing trash pulls I would think the Plating would be better.
For single target boss tanking what would provide better mitigation?
I may keep two shields and switch between the two. Like when I have to take hatefuls on Patchwerk.
I chose Titanium Plating over the defense. While added defense does boost your avoidance, I feel after 20% on dodge and parry more defense past 540 is a waste of an attribute investment and the return on block more worthwhile. Ultimately, it comes down to personal preference.
Execute for show, tank for dough.
I agree that it makes sense to have 2 different shields if possible for different encounters. Making a very high BV set would work well for trash or heroics, being able to switch out for more mitigation and avoidance for boss encounters.
I would think it largely depends on how close to cap you are. Is there any benefit to defence over 540? To my understanding there is, but it's minimal. The benefit of BV is continual, though. In my opinion, def enchants are good to get up to 540, but after that are a good place to start cutting back and swapping out.
I'll be replacing my defence with SBV ASAP.
In my opinion the anwser would be to look at your gear, and situation. If you have one shield and find yourself offtanking a lot blockvalue might be better (tanking welps, doing more damage with your shielslams). It all comes down on how you want to play and if you want to itemise your gear around the role you play.
Quick example about my current sets:
Patchwerk (heroic naxx) shield with +20 defense to put me over the cap as my general tanking shield. Nice avoidance, decent stamina and well enough defense to get me over the cap again.
Wall of Terror - currently block valued out and really only sees use in aoe grinding or tanking loads of adds (the block rating on the shield does help)
The stratholme shield is in my maximum threat set where I've itemised in as much hit and expertise as I can grab, without losing too significant amounts of health. Costs me some avoidance overall though.
You may very well not want to create different sets and just make one overall best tanking set, for example if you don't have a lot to pick from or simply do not want to. I know a lot of tanks that just do that and look at me with big eyes and say - are you ehm like ... whazzat? Note that that isn't exactly optimal, but in the end choose what fits your playstyle.
Well anyway, creating different sets for different situations is what works for me. (if only because I love playing around with stats optimising what I do) Hope that sparks a couple of ideas.
Depends on your situation, but I have 3 shields with the 3 new enchants for different scenarios. Most commonly I use Barricade of Eternity with the Titanium Plating, and have found it to be working well so far. I've also got a Wall of Terror and a Hero's Surrender with +20 Defense and the Titanium Shield Spike as secondary shields. If you're struggling for defense to reach 540, then +20 defense is definitely the way to go imo on any shield, but if it's not an issue, I've been liking the +40 Block Value so far.