Really? Personally, I find Ares friends to be much safer. Sure Shiva gives a higher attack multiplier, but Ares givles a double orb change, which provides a much larger burst than Shiva's orb enchance. Of course, I'm assuming that you're using your tyrannos and and you're not row spamming.
Oh no, don't get me wrong, I'm still using my Ares Friends quite a bit, it's just the more I play, the more Ifrits and Ifrit-Like-Monsters I have to deal with and since I have to save my big burst for the boss (but can't go through the monster's defense without it) I'm pushed to Shiva.
I don't really use Shiva for the Orb Enhance myself, I have Horus for that.
That cooldown reduction is MASSIVE though. 35 ->22. You actually stand a chance of actually using it in harder dungeons. As someone who uses Hera-Is in Kirin, stalling is not fun. It doesn't exist for me most of the time. It also provides an on color draggie with better stats and a mini gravity tacked on for free. For most dungeons(the ones that don't have huge tanks like Zeus), it'll do more damage than the gravaties. My main disappoint is the loss of the row boost and the fact the cooldown is still pretty big. I hope he gets buffed.
True, the lower cooldown is going to be the biggest factor (though skilling it up will be even more impossible than Zaerog's 35% gravity). Though if you're using Zaerog as a sub you'll have to deal with his pitifully low stats (unless this uvo gets a massive stat boost, which probably won't happen since that already kind of happened with D/D Zaerog) and amazingly huge exp curve (How many more monsters have a 5mil exp curve, again?). What's even more egregious is that Draggie gives a bigger boost at a slightly lower cooldown (which can get much lower) for what will probably be only slightly worse Weighted Stats and less than 1,3mil exp to max. I mean, sure, Draggie's off-color, but it's still pretty stupid.
As far as using him as a leader goes, you're essentially better off using regular Zaerog since he gets a conditional x3,5, instead of an unconditional one, and unlike D/D Zaerog he doesn't give x1,35HP either.
Which reminds me, when are the Zaerog buffs coming to NA?