Shaman AC importance vs other stats?

[garfo]

Theoryquesting here -- because there's no way I can afford all of these items -- but I was just looking at the numbers of a Lodi Shield + Hiero Cloak combo vs a Lodi Shield (on back) + Orb of the Infinite Void combo.

With the orb + lodi, you get 25 more AC. With cloak + lodi you get roughly equivalent stats, minus the 25 extra AC... but it's 8-10k cheaper.

So the question is: how big of a different for a mid-50s shaman would that 25ac make?