To be fair to the LuxuryLite V Bag, it two-layer lofts at a full 4-inches. The 8cm loft was the minimum loft specified to the manufacturer but they have exceeded that with 4-inches loft as stated on their web site. And the bag I bought did measured out at four inches and it weighed 1-pound 14.2-ounces. It cost $125 plus $10 shipping/no pillow. That was about the first of November, now it is on sale as a package deal now listed at $165 with the 2.5-ounce air-foam Ultralite Pillowpad.

I don’t disagree with you about fill power at all, but I can’t measure it without removing down samples from the bag. As I ain’t gonna do that-I have to use loft and weight and compare same size bags. And according to Western Mountaineering, fill power can vary a full 10%. So 850 down would be anywhere between about 810 and 890.

Here are some more comparisons:
Two 20-degree bags @ 6’6” long x 32” wide x 5” loft:
Campmor 20------20oz. of 550 down-----38oz tot.wt---------$120
WM AlpinLite-----19oz. of 850 down-----29oz tot. wt.-------$400
Difference----------1oz.------------------------9oz-------------------- $280
I understand the difference in total weight due to the heavier fabric in the Campmor bag, but I don’t see how 20oz. of 550 can equal 19oz. of 850 down? And the equal 20-degree rating when the AlpinLite has a down collar and the Campmor does not.

Two 30-degree bags @ 6’6” long x 30” wide x 4” loft:
LuxuryLite V Bag-------?? oz. of ??? down----30oz tot. wt-----$125
WM SummerLite--------10oz. of 850 down------21oz tot. wt.----$260
Difference------------------??--------??-----------------9oz-----------------$135

Looks like it is going to cost roughly $100 to over $250 to save less than a pound and get close to that ultimate sleeping bag. And in the long run it may well be worth it. A well made, well cared for down bag will last just about forever. So an extra couple of hundred bucks prorate out to a couple of six packs per year. There are a lot of other things to consider in choosing a bag then what a simple chart can show, such as quality of workmanship and materials, comfort and fit, extra features, and good sales when you find them. And I don’t want to give up my center zipper