I've been using the Dragon DX for a long time, and never had any problems. They do fog up occasionally, but only when I get a lot of snow inside (i.e. face first in pow).
As for lens color, I use:
Rose for low light condition, overcast/cloudy days. They help to bring out shadows in the snow so you can see the variations better.
Mirror tint for bright, sunny days. They have a darker tint, and the mirror helps to reflect additional light.
Orange for a mix, good for changing conditions. I hate to use the rose when its sunny and mirror tint when its cloudy, so for the days that will be both, I go with the orange.
Yellow for nights. They help brighten up the darker areas.