Well, I'm no pro...
I think it's important to realize that I'm not fantastic and have only had my own equipment for a short time, so maybe I'm just doing something wrong. These boots are toasty as hell, and you can you get them really tight to your foot. But, they're huge and they chafed the top of my foot a bit, and really hurt my calves during my runs. I'd have to sit and rest at the end of each run, and I never had that issue with the rental boots I used to use. I'll probably try to find something better for me, but I like looking like a character from Gears of War.