Yes, yes, absolutely yes. Take it from a woman who easily gets cold. I've had the Hotronic heaters since they first came out. I always had cold feet, so cold that I'd take my boots off after an hour and wrap my feet in a sweater, they were very close to frost bite. Now my feet get cold at the end of the day when I'm tired and hungry.
I was at Copper Mtn over the holidays and the temps were in the teens. Lots of people complained of cold feet but not me!
Sorry, I don't buy that if your boots fit well you won't have cold feet. My boots are an awesome fit but they're still cold without my heaters!