Re: *** Official World of Warcraft Thread ***
There isn't a big difference between protection and arms/fury in terms of tanking. The only important differences are shield block and last stand. With that shield from MC and one of the bonuses from the might set, you can start blocking for 120 or so everytime, which ends up being significant when improved shield block allows you to block 2 attacks.
Last stand is good in those "oh ****" moments, and makes a difference in certain fights.
None of the 5-15 man instances require you to go protection. Heck, it's pretty damn stupid to go protection on a pvp server as it cannot compete with arms/fury build PvP wise, and it doesn't make that much of a difference compared in tanking.
If you want to tank and still be very effective in pvp. go w/ the usual 31/5/15 build, that's what my guild's main tank uses, and that's what I would use if I didn't PvP much.
There isn't much in the protection tree that allows a full protection warrior to survive better than a warrior w/ 15 points in there, so what makes other warriors last longer is that they have more +defense gear. At +125 defense, you have 5% more chance to parry, block, and I think dodge, and reduce another's chance to land a critical hit on you by 5%, reducing the burst damage mobs can land on you, which helps a ton.