I just received my package from Joe at ZPacks which included a few more cuben fiber stuff sacks. I was able to drop just a few oz by replacing some of the product's supplied stuff sacks with the lighter weight cuben fiber stuff sacks, so that is cool.
Joe's stuff sacks are really great. Lightweight, and actually not that expensive. If you compare his stuff sacks to other stuff sacks which are around the same size, the price isn't really that much more, so why not go with the cuben? I have been very happy with mine so far.
Anyway, here is a write up of the sacks I replaced and how much I saved off of each one and a video.
Cuben Fiber Stuff Sacks = Less Weight