So with 1.9 released, I again stay up far too late whacking training dummies in varying stages of undress trying to wrap my head around this scaling bs. I know most people don't give a shit about mechanics, but I figured it was worth posting for those that do.
That being said, Pet Scaling follows a pretty simple formula:
Damage = Base Skill Damage + (Pet Magic Boost/Rate)
With the rate changing per skill, per pet, and per tier. After some testing, I worked out the damage rates of each pet at 50. Skills I tested with were Thunderbolt Claw, Disturbance, and Detonation (Flow would have taken far too long for tonight to test).
Code:Claw Dist Det Fire IV 1.62 1.06 .757 Wind IV 3.88 1 .71 Water III 1.5 1.02 .825
To see how much of a damage difference this is, just plug your numbers into this formula:
Damage - (Pet Magic Boost/Rate) = Base