Both machines had clean filters and empty bags. Both did identical passes on an identical piece of carpet with the same measured amount of soiling. It was a fair contest. "The Sebo won hands down" It removed more dry soiling than the Kirby. The reason the test was done is because I was curious. Believe it or not, 18 years ago I started out with a Kirby and 40 own made leaflets. I bought the Kirby from myself as I realized that people wouldn't spend all that money on a vacuum cleaner but would pay to have there carpets cleaned. I used it for about 3 months with Kirby shampoo then went to Prochem Foam Shampoo, made my money back, then after learning more I purchased my first HWE machine from Ace Janitorial in Sheffield... A Prochem Steameasy 400. It was a great machine and I run it for about 3 years before selling it on then buying a twin vac Prochem Cheyanne. I now run a dual operatored truckmount a multi van operation with various twin vac portables for wet and dry cleaning. I am now also putting my son through a carpet and upholstery cleaning apprenticeship.