An odd, niche item
An interesting idea but this item steps into a market which is already filled with outstanding warm weather bags. Why carry a large, nearly two pound bag that doesn't compress well? ALso, because this bag lacks a mummy hood you'll be losing a lot of the heat which a 35 degree bag might have retained.
It makes much more sense to invest a little more money in something like the Marmot Atom/Hydrogen or Mountain Hardwear Phantom (32/45). If the temperatures are too warm just vent the bag, or else use it as a quilt.
If you can't stand the confines of a mummy bag and you'd rather flip a bag over than unzip it, this will probably work for you.