In concept, pets being able to cast chiv, magery, spellweaving, etc sounds pretty cool. But then I thought about it and I am avoiding it like the plague. Since you cannot control what spells they cast, what's the point?
I'm sticking with AI, Rune Corruption, and other special moves that you know for sure what you're getting. I'm also keeping it to 1-3 things max per pet. That way they're more likely to spam AI or whatever and I know what I'll be getting.