I honestly don't know if you can beat this bag in terms of warmth for weight. I bought this to take on the John Muir Trail in August 2019 (high snow year) and was seriously impressed with it! The bag comes with a stuff sack (not a compression sack) and the storage sack. The packdown size is incredibly small and I was able to fit my sleeping bag, Big Agnes AXL pad and my Nemo Fillo into the bottom portion of my pack that was normally be completely taken over by my previous sleeping bags.
To cut down on weight the bag has no draft tubes or any other frills, but I did not have a night where I felt cold on trail. I don't know exact temps but we slept above 10,000 ft every night and the nights were cold enough for frost to form. I would definitely recommend this for any summer backpacking adventures or some warmer shoulder season adventures.
As mentioned in the description this bag is cut on the narrow side. If you're broad in the chest/shoulders check out the Caribou!