I'm 6'2" about 230lbs and I wear my normal size in First Lite (XL top and bottoms).
Unless the Kanab 2.0 pants have changed a lot from the Kanab 1.0, I would not consider them a cold weather pant. The Kabab 1.0 is not insulated and is constructed from a fairly durable, yet relatively thin layer of merino. I use them in warm weather with merino boxers and in cool temps with a full length pair of merino bottoms. I wore them a lot during turkey season last year when it wasn't raining. For cold weather my Kanab pants stay home. Of course much depends on whether you're mostly sitting still or mostly on the move. On an active hunt they could certainly go colder.
The Puffy is warm, but not down jacket warm. I love how light and packable it is, but the trade off is that the lightweight outer layer isn't the least bit quiet. I only hunted one really cold day this past season, and I used the Sanctuary jacket which I bought last year from Midway USA during their end of season closeout sale. It's super warm with an impressively quiet outer layer. However, it's much more bulky and heavy than the Puffy. The Puffy can work in both active and stand hunting scenarios, but the Sanctuary is really only practical for stand hunting on really cold days.
