I used to have a couple of Karcher Puzzi's many years ago for hiring out. To be realistic, your friend would be OK to use it for keeping the bedrooms clean in the hotel, but not for getting them clean. If there are enough bedrooms, it could pay for itself. Elsewhere, it could be used for spots and spillages, but is not suitable for use in high use/soiled areas. The carpets would be overwet, with subsequent H&S issues as well as the risk of shrinkage on wovens, and stretch/delamination risk on tufteds. As with professionals, it is essential that he pre-vacs SLOWLY first with a good quality upright vac.
Safe and happy cleaning:)
Ken