Doppleganger silver mod on the 360

[night drow 0]

I heard the silver mod on the dopple pet wasnt working or something, I dont know. What I want to know is if I choose for him to be astute style dopple will he sit back and cast spells? And will he increase in effectiveness if I choose for him to be astute when ill be mastering astute lore and focus?

 

Or should I skip all that and just choose him to be gruesome spec and make him melee and he will just increase in effectivness with runes?