Well, when it comes to making the choice between the elements, I have one simple thought:
Pet WD never lack single target dps (ie elites and rift bosses). Never. They die in seconds no matter what withGargantuan and BBV.
What we lack is AOE, and this is really annoying in open space with tonloads of little mobs. Our fetishes and dogs start to kill them one by one, running around and it takes so freaking long.
I've tried Zuni w and w/o Kukri, phys, poison, dart mask, you name it. The most effective choice (xp and items per hour, clearing speed) is:
Ren'ho with explosive toads + fire + big dog on T5. Unity is useless (get serpent). Even Sodj is useless. Just get shitloads of plain good dps, put some +fire on amulet and bracers and you are done, everything in sight just dies. You don't need control, you don't need life leech, you just smash with fire.
Why T5? T6 is just not effective: takes too long, there is risk of death, you need to adjust gear for more hp-armor-mitigation. Not worth it, just clear T5 as fast as you can and you are fine.
Sorry for my english dudes! )
Proper placed Piranhado + Soul Harvest (Vengeful Spirit) and every little trash mobs dies instantly...
Rofl the charging adds that one shot you on T6 through your sharknato say otherwise. Nearly every elite @T6 and a surprising amount of non elites have ways around this attack. It is amazing for party, but if your running anything other than Jade at higher torments I can't express how ineffective this talent is.
Taking it or not taking it is up to the player, I would suggest that many people do use it, if only to see how effective it really is against a rift full of adds from act 5, or large white mobs. Never mind elites at T6 they are usually too large to even be affected by the knockback effect, negating strongarm bracers.