Seems like mp1 is faster then mp2 even though u get more xp.
I'm simiilar except i think you'd be much faster if u swaped your soul harvest to vengeful spirit. Reason being is it has no casting animation and you can run through with spirit walk cast and keep running. I post an example i just randomly did.
http://www.youtube.com/watch?v=LosnrDfBNiA
i usually spirit walk, vs, then acid to finish. Or acid spirit vs.
4 runs 0 legendaries
