Remember that the anthem are wider then the average park ski. This adds some weight to the ski, although the ski is pretty light even with its wide profile. They aren't lighter then the afterbangs, if that is what you wanted to know.
Anthem look like awesome skis, I ski with some invaders and they are great (unfortunately, they aren't produced anymore). Anthems are like the wider version of the invaders. They will be better for powder then my fellow invaders. As an eastcoster I don't get loads of snow...
171s would be a good size for you, remember that line measures their skis differently then most companies. They measure the "running length" the part where the skis touch the snow, unlike most companies that measure from tip to tail. So your anthems should be 176 from tip to tail.
