Since switching to the Iolite screen, my Firefly is hotter.
Another "Firefly conundrum"...
I find the 7 hole Iolite screen makes my Firefly run cooler. I use it in my Silver FF (which runs hotter than my Grey) to prevent combustion.
I've had uncontrollable combustion in the Silver, but none since I started using the 7 hole Iolite screen (knocking on wood).