I have 3 of the micro weight ones that I use for base layers, especially for x country skiing. I also wore them for running last spring.
Perhaps I will buy the zip version; the issue is that it doesn't have pockets. I find that at this time of year, with my light wool jersey, if I wear it with a Craft base layer (anything from sleeveless to long sleeved), it serves me in a wide range of temperatures. But, I guess when the pockets are added, it becomes a cycling jersey and the price gets jacked up about 100.00!