I saw those in one of the catalogs this year and had to do a double take. If you have the cash, and a serious circulation problem, I think they'd be worth a try at the resort, or a place where you are not going to be in trouble if they fail, or run out of juice (aka - not the backcountry). That said, I think good gloves/mittens are important, but we often forget that we can help keep our extremities warm by keeping our core warm. In other words, a thicker/additional baselayer, or vest can also be a way to deal with cold feet and toes.