Mage specialization (with a twist)

[Hakubi]

Mage just hit 20, debating between Evocation or Conjuration spec.
I probably won't be taking him past 51 or 52 and just parking him at some cash camp
like Lguk or Droga which means using 49 fire pet and my last nukes being:

Evocation Single target 810 DD @ 300 mana
Evocation PBAE 608 DD @ 361 mana
Conjuration Single Target DD 600 @ 250 mana

I'll probably never cast a CoH in his life or summon a rod outside of leveling to that point. Would I still be chaining pets in Lguk to warrant going Conj or should I just go Evo for better leveling / AE? Would his farming efficiency go up at 60 (without elemental staffs) to be worth the time investment? What level would I be able to take Frenzy or Droga content with little difficulty?

Is Dyzil's Deafening Decoy any good at 56 assuming never getting ele staffs? I might push him to 56 if so... or 60 IDK.

TL;DR
optimal farm bot level and spec?

Thanks.