for Fogtech (and I've tried everything)... I use it on my eye glasses. Only problem I find is that it will collect enough dust by the days end to impair vision. I've got the Nolan fog insert (I believe same material as fogcity) so no probs with the visor.
I do have a Respro mask but haven't used it yet since I'm not crazy about the idea of leaving an open air channel down the front of neck, chin and mouth in below freezing weather. But I'll have to give it a whirl when it get real cold.