I used the AK Oven Mitts for two days at Killington, VT. First day was about 30 degrees and the second day 18 degrees (not factoring windchill which was whipping the two days). I am not a heat producer and get cold pretty easily. After reading about all the rave reviews on the Hestra Heli Mitts, I gave those a try but they didn't do the trick even when I used hand warmers. So with the great service and recommendation from the BC folks, I got these mitts and can finally feel my fingers.
My hand measurement (width) is a 3.25 so I decided to get the mediums just to have a little more room. They fit very well even with the added space, however, when I included a liner, it ended up being a little snug. If you decide to wear a liner (which I don't think you will need) you might want to size up but if you size up and end up not using a liner then there might be too much room. Also, if your jacket has wrist-gaiters, it might be a little annoying if the gaiters aren't skin tight because it might bunch up since these are under-cuff mitts. I didn't try to fit the gaiters in the mitt, I just pushed the gaiters up into my sleeves which made taking on and off the mitts without trouble.
The mitt seem to be very solid and very warm. With all the insulation packed into it, there wasn't a huge lack of dexterity (well as much as you can get with a mitt anyways). I was a little hesitant about the individual finger slots but to my surprise didn't affect the warmth. The only time my fingers got remotely chilled was when a tiny bit of snow got into the mitt because I took them off and snow was blowing. My hands warmed up quick whenever I had to take them off and on. I wouldn't hesitate to get these again if anything happens to my current pair. Happy with my purchase and great service.