Even though I am very happy with the looks of this mask and the protection it provides, I have to say that it is a nightmare to keep fog out of my goggles.
I play CQB and run a hell of a lot, and sweat a lot. I also have to wear a balaclava under my mask, otherwise, it's not comfortable, which also adds to the steam factor.
I use ESS V12 on open position, with cat cr@p. Still, fogging gets really bad in only a few minutes.
The only solution to this issue is to use mesh goggles. Otherwise, if you sweat a lot, forget it...