I have an Elite 2 rated down to -5C (23F) and I can confirm they are overly generous in their assessment of warmth.
This was confirmed when I spent a very cold night when the thermometer dipped below freezing and I had to drap my coat over my legs and put a heavy jumper on inside the bag. I have now replaced it with a much better Exped down bag. In Europe rating systems are serious business so you can't just claim a rating it has to be independently tested. Mine is rated down to -10C (14F) comfortably, and it weighs less than the Snugpak!
EDIT: after doing a bit of research just now it appears that Snugpak have revised it's stated comfort levels to 0C.