There are two ways to go about doing this. The first way is more math involved and a bit of a roundabout way to approach it. It involves determine how much of a DPS gain/loss you get from running 7 Divines instead of 4 Divines using the Thief/Shadow and comparing that to the DPS gain/loss you get from running 3 Infused versus no Infused.
Very roundabout, but it gives us a good idea whether it's worth pursuing our second method.
Our second method is just straight up comparing the ability metrics between the two. This requires a little more care to set up the equation properly, but it should give us the exact value by which Infused beats out Divines (or not!).
As it turns out, with the assumptions we make in this calculation, we get that Infused is better than Divines by 0.01 percent.
Yep, less than one tenth of a percentage point. If you're already running 7 Divines, it's not worth the effort to transmute. Watch the video below for the math.