I have found both on my Warrior and my Monk that AC really didn't make too much of a crap till 45ish. Then it DID matter in the 50's, not a ton, but it does make a difference on how Hard you get hit. But with Kunark gear and the soft cap having tons of AC on here is not even obtainable. Velious will change that though.
Even on live now you have to have a AC aug in every slot to see a huge difference. But the problem is every expansion the mobs hit harder and harder so you really don't gain crap unless you go to the old zones.
[You must be logged in to view images. Log in or Register.] And since Cleric CH will never heal for less than what anyone will ever get HP's wise it is sort of moot.