I've had this helmet for quite a while and still don't regret my purchase. That said it has a habit of doing something worse than my old RF900: internal fogging.
The mornings that have fog as an issue are colder mornings (typically below 58F). The system setup to deal with this includes a vent at the chin level and one at the top of the forehead. While those work for traveling at 60mph+, they're worthless under that speed. And if you yawn or heave a heavy breath for whatever reason, you're screwed. The only solution, really, is to open the shield a crack, but then you face freezes.
The breath guard has no significant value because it depends on you breathing through your mouth, which most people try to avoid on the cold mornings since the increased humidity makes your face (and forehead) even colder.
The chin curtain does a good job of keeping my chin and face warmer, but also reduces the defogging effect designed into the helmet. So, again, you're forced to open the lid a crack which partially defeats the point of having the curtain in the first place.
Having to crack the shield one notch can be offset slightly by looking more through the top of the shield which causes the air to divert around the shield and thus reduce the freezing effect.
This morning I played with the settings and found I like actually SHUTTING the lower vent and riding at >70mph (indicated). It was enough to keep it reasonably clear, barring heavy breaths. I wonder if that'd be a viable excuse for speeding
I haven't tried any of the anti-fogging solutions on the market yet but will get some before next season and try to remember to add to this with any helpful hints. Recommendations are always welcome
One last thing: on these cold mornings I always close the two vents at the top and back of the lid since in the past I've discovered this helps to force air across the face shield rather than diverting it across my face and head. It also keeps things nice and warm.