Hey Chris,

I'm not in Front of my Catalyst, but If I remind right it's the Decklink Extreme (not the Intensity and not the HD Version)

And there is nearly no visible Latency.

Frame Dropping appears only when Workload is too high for the Macpro.

A funny thing I encountered was a "Chase" of Stills over 6 Mixes with just 6 Layhers, means the Images switched to next Image in the Library and Live Video did a Fader over some screens on and off.
In the Moment of switching to the next Image the Live Video had Framedrops.
I stopped the Image Chase and no more Frame Dropping appeared.

Best

Rolf