The Large carrie hoody fits me beautifully over one or two shaks. I'm 5'5" 148 lbs.
I might fit into a carrie hoody medium but I wouldn't be able to wear much under it. Then too I am small busted. (hey there's that song again!)
KNot-I think the Carrie is just a bit warmer weight fabric than the shaks. But both are wonderful. My carrie hoody goes wonderfully over a shak. I've been wearing my emerald green Carrie a lot lately.
Dianyla- my half zip black shak has the thin nylon-y zipper as you describe. My (also new) black full zip shak has a slightly heavier metal zipper. I wouldn't call it sharp or toothy though- more like a "regular" zipper. definitely bigger than the 1/2 zip's though.