They changed how Pet:DA works with blood pacts a while back. It used to be basically worthless, then sometime a couple years back they changed it for multi-hit pacts. So Volt Strike, Predator Claws, etc. Pet:DA is now awesome for those. (Not Flaming Crush though.)
At what rank does +2 neck surpass other neck options? (physical and magical)
Physical without Nirvana AM3: Around rank 18
Physical with Nirvana AM3: Around rank 12
Magic: Around rank 12
Flaming Crush: Probably even earlier, maybe rank 10 or even lower