If they are anything like the lenses on dye's i4's, you shouldnt have any problems with these. I havent had a single pair fog on me. We put those masks through some tough crap.
Did fog through this, when other brands did.
CXBL 2K11 Western E2 At Xcalibre Paintball - YouTube
Also warranty processes with Dye are quick and painless. Especially for people who live in the States. Even In Canada they really do make a quick turn around.
To think they started out making their stuff in a garage. Dave Youngblood has you covered.