JR, I've compared the Patagonia and Kirklands, side by side, as I own both. I love the Patagonia and have used it well. My only complaint is that the shell is so soft that it tears easily and I have repair tape on both cuffs and inside where the stuff pocket zipper snagged it.
I bought the Kirkland because I could tell it was a screaming deal after I checked it out in the store and I wanted to test it out to see whether I could recommend it to my fellow Scout leaders and some of the larger youth. Since starting this thread, I've worn it many times, stuffed it down twice, managed to find myself in heavy fog without a shell and come to like it very much. The shell is more durable than the Patagonia, oh and the "Scout Green" version is spot-on in terms of color. The interior pocket is smaller, is not mesh and does not have a two-sided zipper–it is not a stuff pocket– and this is the primary shortcoming of the jacket.
The fit between the two XL's I own is nearly identical and the methods of construction ARE identical. Stitch placement, cuff material, etc… all the same (as if there's much room to vary).
In terms of weight, the Patagonia weighs more. I tared out a hanger and put them on the digital scale:
–Patagonia Down Sweater: 16.1oz
–Kirkland Down jacket: 13.1 oz
I think it must be fill, because I can't believe the Kirkland shell cloth weighs less than the softer, thinner gucci stuff. It hasn't been cold enough for me to discern the difference.