I own the Down Inner Parka and it keeps me warm down to around 30 degrees with a Capilene 1 baselayer and a Marmot Ion windshirt underneath. With a heavier baselayer (Cap 3, R1 etc) then I could probably be comfortable into the low 20's.

My wife owns the Downlight sweater and her experiences have been similar. I think the that the First Ascent piece is probably a little warmer than my Parka, but not by much.

All in all, both garments are fine bits gear and are excellent three-season items. You won't go wrong with either purchase and $85 sale price for the Downlight is a steal if you ask me.

If you are wanting a true winter piece, then you either need an additional layering piece to use in conjuction with your above purchase or something more substatial like the MB Alpine or Fugu Jacket.

FWIW, the UL Inner is a little warmer than a Polartec 300 fleece. Interesting study.