That is an interesting article--good information.

Since there's no independent lab testing bags from everybody, I limit my temp ratings comparison to within the company's line, i.e., I'll take it on faith that company X's 20-degree bag is warmer than their 30-degree bag but won't presume their 20-degree bag is as warm as company Y's 20-degree bag. Design and size considerations play a part, of course, and the bags need to be used across a variety of conditions and scenarios over time.

From the emperical data playbook, I can hit or exceed Western Mountaineering temp ratings comfortably. I have not found the same with Montbell (to pick two popular companies).

Cheers,