I've been researching down bags online via specs (no stores near me) and tons of good advice and opinions gathered here (thank you all). Being a numbers-type person, I set out to develop a simple but meaningful method to compare different bags based on specs. Essentially, I was trying to do better than just comparing the temp ratings of one company with those of another and hope they were comparable. Instead, I've considered the amount and quality of down used along with the dimensions of the bag. I (only) looked at 17 bags from a 6 manufactures but remarkably, the results look meaningful and interesting (to me at least). Have a look if you are interested and comments are welcome!