Sorry didn't mean to imply that you were attempting to formulate the game ^^
I agree with what arlee said if you're not building an evasion pug.
Just look for def and m.def gear, and use what's best for the situation.
Like if you're doing an imp or elemental leve, then you'd want to use more m.def gear obviously ^^

As for evasion, it may get re balanced, atm it works well on some mobs, and poorly on others.
Toads, and Mongrels are great to use evasion on. (just to name a couple)
Other mobs straight def will win out because of the accuracy, or m/def because you simply can't evade magic.

Also another thing I don't think has been mentioned, and that I failed to note myself is HP gear
Since you only get around 5-6 per point of vit from 100-128 (haven't checked to see if it's a steady or diminishing return)
HP gear can easily replace several stat points in vit that would otherwise offer little to no change in damage reduction.
Just don't go crazy and hurt other stats. (but most of the high def gear has +HP already)

Cheers