I'd go with jpc on this one Petra. I used to run a couple of the early Karcher Puzzi's and found them excellent for spotting, small single room jobs which weren't too challenging, and for the hire market. Ideal for car valeting too. I don't know if the design has changed, but the recovery tank lid on some models had a small rubber 'O' ring which was easily damaged. Don't use the waste water bucket to carry clean water from the tap, get a seperate bucket.
Safe and happy cleaning:)
Ken