That bag looks nice BUT the limit rating is to -16C/3F. Usually if you want to be comfortable and not just survive the night you should look for a comfort rating at your expected temperature. That said, some people sleep warmer than others. I know I’ve had enough nights of barely sleeping because I was so cold that I mostly prefer to avoid that situation now.
I have personal experience with Feathered Friends and they are amazing bags and super lofty. I would trust their temperature ratings. I’ve heard the same about Western Mountaineering over the years.