Levi wrote an answer about Arc'teryx Khuno Insulated Parka - Men's on September 10, 2012
I have a Venta AR which has wind stopper and a fleece backer and it is warm down to about the mid 30's. I add an Atom LT which only has a 60 fill core loft and that takes me to the upper teens. Below that I use full GoreTex Pro insulated with 80 fill core loft. I say all that to say the new N80x wind stopper and a140 fill of core loft of the Khuno Parka should be incredibly warm and should easily take you down to single digits or below. I think the Fission SV would be the only other coat to consider but it is not nearly as urban design friendly and runs another $200 more. I hope that helps.