Good choice..
For me, I wouldn't take that under 15-20. I get below that I'm cold. Including socks, pants and jackets up top.....
Some can do a bit colder than that. Depends how you sleep .
Quite a few of the bigger quilt makers use the European rating system, called the EN. The temp rating is where it will keep you alive, not warm. You generally need to add 10 to 20 degrees to that to know where it will keep you warm. The ISO rating is almost identical to the EN. I believe they just get it a little differently. When you get a bag rated other than EN/ISO, you don't know what you're getting. That doesn't mean they aren't good, it's just that they're not using a set standard.
