I love the way the boa adjusts the boot to fit my lower foot. I get a great fit with no pressure points, and I can easily adjust them throughout the day. I have a short foot (23) with high arches. I went with the 23.5 in these (some 22.5s fit in different brands, but the K2s I've tried are just a bit too short in a 22.5) I've skied 10 days with them so far, and I'm very happy with my purchase. Last year, I bought K2 BFC 100s with heat, but I traded them for these because they were too large/wide and had too much flex, which affected my skiing. Several people where I work as a ski instructor have commented on the change in my skiing since I switched to better fitting boots. I had these heat molded and adjusted to fit my feet and stance with the included inserts. My feet don't tend to get cold when I ski, so I might not be the best judge for warmth, but these (paired with smart wool socks) have kept my feet toasty for hours in the few days we've had of below zero temps. For comfort, fit, performance, and warmth, I give these boots 5 stars!