So, it pains me to see it, but my dad is getting a little older. He is still probably the toughest waterfowler I've ever met, but in the last couple of years his circulation is not what it used to be. the other night, he commented to mom about the gerbing heated blind seats he saw advertised on a hunting show. has anyone used these? i tried battery heated socks once and they were worthless, and the battery kept banging me in the legs. these seem like a good idea though. any thoughts? do they work, or is it a gimmick?