I ride NY, VT, MA, and PA all of which are hard packed at best icy on average and boilerplate at worst. I own a Legacy and have ridden the dark, skunk and the old 11up all with mtx or btx. Add to that the fact I'm like 270lbs and let's just say I put pressure on my edges. The vario is definitely not as grippy as the vario but I like the vario better. As BGilly said it just transitions edge to edge more naturally. Also if conditions are boilerplate it doesn't matter which one you're riding, you have to point it and barely work your edges anyway.
As far as the difference in dampness, truthfully my gut tells me you will barely notice the difference anyway. Yes the NS is solid and plows through crud but we don't get enough snow outside of jay to really have to worry about that. The bs snow piles at the end of the day can be charged through on 1984 Burton backhill just fine.
Both brands make good boards. I went with NS because I wanted the 3 yr warranty and I prefer their take on alt camber