Overall: The Ratio series of bags from Mountain Hardwear are filled with 650 Fill Power hydrophobic (Q Shield) down. Hydrophobic down means that your sleeping bag is less susceptible to moisture compromising its performance, this can be important on multi-day trips if you don't get a chance to air your sleeping bag off properly. Its also useful if you are going to be using the bag in damp conditions, especially when using a bivy or tarp when there is more chance of the bag getting wet than in a tent.
650 Fill Power is good quality down but not the best, its used because its cheaper than higher Fill Powers, but it doesn't perform as well, however the difference in performance is fairly small and if you're on a budget the Ratio is a good quality bag and still very light given its performance characteristics.
I used the bag on a recent trip on the Cleveland Way and it ticks all the right boxes, it feels roomy and has a full length two way zipper, this means its easy to ventilate the bag when you need to, there's a decent anti-snag strip down either side of the opening and a baffle to prevent the zip becoming a cold spot. A boxed foot keeps your feet comfy and the full hood can be pulled tightly around the face. It has a baffle round the opening which helps keep the air still in that area - in turn this protects your nose from the cold more than other bags without this feature.
Rating-wise the Ratio gets a Comfort Limit rating of -3C, which is amazing for a 650 Fill Power bag that's this light - however we have some comments on this - see below.
Performance: This is a difficult review to write because I have a lot of faith in the EN testing regime and yet this bag doesn't feel as warm as the test results would suggest. It not a blind faith I have in the EN results, its from many uses and reviews of a lot of different sleeping bags, and although my view of the Ratio is anecdotal that's what I felt about it. When you look at the amount of down used in this bag its the same amount as other bags that use 800 Fill Power down, not 650, and yet the Ratio gets the same temperature rating as an 800 Fill bag, so there are some figures to support what I'm saying.
I don't want to put anyone off though - the Ratio is a very good sleeping bag that costs about two thirds of the price of bags with higher quality down filling, with only a small lessening of performance, buying a Ratio bag could allow you to spend more in other areas to upgrade your kit.
Other Comments: I stuffed the Ratio 32 into a Granite Gear Air Compressor (XS) and compressed it fully, the resulting pack size was 24cm x 14cm diameter, this is pretty impressive and compares well with other bags that get a comfort limit rating around zero.
The Ratio bags are good quality with features that you find in high quality sleeping bags but with a lower Fill Power down to keep the price down.