I've used the Patagonia down sweater (hooded and unhooded), and recently switched to the Montbell Down UL Inner Parka. I loved the Patagonia, and am highly impressed with Montbell so far (one cool-weather trip, so far); I also got the same Montbell pants another poster mentioned.

The Patagonia is warmer (more down - at a cost of half a pound over the Montbell), but both work as part of a layering system that works well into the lower 40s. By the time it got that cold, I was ready for bed (a WM Megalite 30 degree bag); the temperature dropped to an overnight low of about 30. I haven't had the chance to try, but I suspect that the Montbell jacket and pants worn over some midweight longjohns will extend the range into the low twenties.

I like the hooded items better because they also add extra insulation to the hood of my bag, and they do a better job of holding heat on the back of my neck and head.

A down jacket is a much better choice for in-camp warmth than a heavy fleece layer - it's lighter and warmer. I've never worn mine for hiking, though - I tend to hike in midweight longjohns under shorts and a T-shirt or windshirt, which is usually warm enough while I'm moving; if I want a little extra warmth, I layer my rain jacket and pants over them.

This system seems to work well for me, and I hike from about the end of March through late October, in southwest Ohio mostly, with maybe 1 weekend trip between November and February, if there's a bit of a thaw.