Last fall we had plenty of fanfare regarding the new polartec power dry high efficiency fabric used in these baselayers - because it's significantly lighter than the previous iteration of power dry but still quite warm, and promised better wicking and dry times along with patagonia's latest in odor resistance. Basically, it's pretty cool stuff and would be a good option if you are looking for a lightweight fleece for 3 season or baselayer in winter.
David Chenault started a nice thread about the hoody here (to sum up his opinion: "A new classic."):
The zip-neck is obviously the lighter choice due to lack of a chest pocket, slightly shorter zipper and no hood, but you lose out on all those extra features. Patagonia direct quotes weight at 6.3oz for the zip neck and 7.8oz for the hoody. I've finally gotten around to ordering one of the zip-necks up now that they're on sale for a more reasonable price at backcountry.com's outlet site, and figured the sale was worth sharing with the community.
Use coupon code 6AS-1-UGL9A (enter it as a "Redemption Code" during checkout, and don't forget to select the free shipping option) to bring the discount to 40% off MSRP.
Link to Zip Neck (limited colors, but S-XL available at time of posting):
Link to Hoody (limited colors, only M + XL available at time of posting):