Well, after reading many Threads about Soft Caps and calculation of the mitigation of Adds, i'ce come to the Clue that ArPen is surely worth it, to go for it. But now i have to decide how much ArPen is worth to get.
I readed that Soft Cap for Minions etc. in T2 Dungeon is ~12.8% and it goes Up to ~24% atStriker, Leaders and Bosses. Now when i go for around 1.5k - 2k ArPen i would loose 60 - 80 Damage ( due the -Stats in Power ).
I've seen tr with less than 1500 Arp and around 7k power murdered bosses particularly the last boss in Spell where everyone else is busy handling adds and hardly get a chance to put a debuff on the boss.
ArPen is the standard way to increase your damage. This doesn't mean that it's the only way. If the rogue is sitting on 50% critical with Vorpal Enchants, he will make up for it. However, ArPen is a flat out damage increase, and you should opt for 24% overall. That said, 20% also doesn't hurt if you boost your other stats accordingly.
when Armour ignored(ArI)<24%
then ArP=125pts/pctdmg+
when ArI>24%
then ArP=***pts/pctdmg+
Therfore, Armour Pen. is the best stat at all times until cap, unless for some reason another stat is increasing your damage at a lower rate than 125pts/pctdmg+
Comments
think of it this way that less power doesnt scale that much compared to getting ur damage reduced from mitigation.
All you need to know
when Armour ignored(ArI)<24%
then ArP=125pts/pctdmg+
when ArI>24%
then ArP=***pts/pctdmg+
Therfore, Armour Pen. is the best stat at all times until cap, unless for some reason another stat is increasing your damage at a lower rate than 125pts/pctdmg+