We used one in the last house we had.... This house I live in now doesn't even have a chimney Funny really, cos the guy who does clean chimney's cleans carpets too....
Years ago i worked for a company installing wood burners, lining chimneys etc, i had the job of cleaning them, its the dirtiest job i have ever done, the soot gets right in your lungs, and skin even wearing protective gear, plus insurance was quite a bit, many a time when sweeping a chimney the pot comes off the top of the stack and falls to the ground, and that can do some serious damage. So if you are going to have a go get insured, and make sure you explain to customer about loose pots and you not taking responsibility, some of these clay pots are very expensive.