Quote:
As a tank, expertise is worth twice as much to you as it is to dps, because it eliminates dodge and parry chance. It also helps with mitigation (parry haste).
While true, this is very misleading.
All stats will have different weights to them for a DpS. These stats also usually have a sort of hierarchy to them as well, independent of the stat weight.
For example, defense is incredibly important to a tank. However, so is TpS. But, no tank is going to be venturing into a Heroic while not crit-immune. So, while both are important, Defense gets the priority. However, after reaching the cap, TpS boosts will be more desirable than defense until certain levels.
NOTE- I AM NOT SAYING TANKS SHOULD STOP AT THE CRIT-IMMUNE DEFENSE NUMBER.
So, when I begin to gear a tank, the first thing I check for is the above. After that I look at health. Then, I check stats that depend on the class (TpS stats). Once I have acceptable stats in each area, THEN I will start looking at item weights.
Why?
Say, for example, with an Unholy tank spec that Expertise/Hit are valued at 2 points per stat. Now imagine that Defense and Stamina are 3 points per stat.
I NEED to have enough Sta and Def to survive and be crit-immune. All I NEED is enough DpS gear to have sufficient TpS. Expertise is nice because it is great TpS with a small mitigation boost. But, I won't take expertise instead of Defense or Sta. DpS on the other hand can very easily sacrifice AP, Crit or +Hit for Expertise before it is capped (assuming those levels aren't too low).
So, in short. Expertise is great. But, you don't need to hit the cap with it unless your other stats are great.
And, remember, just because your mitigation/Sta/Armor is high enough for the current content for you to focus on DpS doesn't mean that it will be as good in the future dungeons.