...Personally I think this material works best as a bivy where you aren't exposing it to bushwhacking. It'd def be the lightest rain jacket you've ever had, but I'd worry about it;s longevity.
That being said....I know a lot of cottage manufacturers who state on their websites when dealing with thin CF "If you're wondering about this product's durability, it's not for you." <- But that's really tough for a guy like me who wants to know everything. When used as a bivy, do you expect it to last for X # of nights? Forever if you're incredibly gentle with it? I wanna know before I buy one of Steve's Bivys!