The X-C is a long sleeved high collared shirt with a medium-length zipper. It's made of Sporthill's 3SP polyester blend and is rated for 20-40°F. Sporthill claims that it is windproof up to 35 mph.
Last night I went for a run in 34° weather and I can report that the shirt performed as advertised. Wearing only the top, my torso stayed warm even in significant winds that cut through my gloves and pants. The moisture management is also excellent. I stayed fairly dry throughout.
The shirt itself is quite comfortable. The outer face is slicker and stiffer than your average running shirt but the inner face is brushed and very soft. Because the shirt is stiff, it tends to fit a little weird for the first few washings. I thought mine was a little big but after a single washer-dryer cycle, it fit perfectly. (Note: you're not supposed to tumble-dry them so I've been hang drying since, which seems to go pretty quickly. I don't know that tumble-drying did any damage, but since it seemed to shrink it a bit the first time...)
I highly recommend this shirt. It's too warm for ordinary use around California (I have a number of dryline shirts for that) but it's excellent for cold weather sports and definitely worth the $86 I paid for it.
Next time you head North, bring your bike. Some of us need to find a good cold-weather top for cycling purposes :^)
Geek gear reviews are always welcome.