Well interestingly or not, judging by the number of responses I got to the initial post, went to a trade night and spoke to the local rep who supplies the stuff and couldn't get a direct answer and was referred to their literature to make my own decision!
An experienced tiler who works closely with a tile manufacturer and the technical rep from an adhesive company both said that they would use flooring grade chipboard a decoupling mat and tile as normal and for my purposes it would be fine, in the case of a wetroom they recommended tanking the floor/walls as usual.
Hope this is of use to someone else who may be considering it, as others have said the principle of using cement boards as a flooring directly sounds good, but seems not to be a common method and I am not sure why?
An experienced tiler who works closely with a tile manufacturer and the technical rep from an adhesive company both said that they would use flooring grade chipboard a decoupling mat and tile as normal and for my purposes it would be fine, in the case of a wetroom they recommended tanking the floor/walls as usual.
Hope this is of use to someone else who may be considering it, as others have said the principle of using cement boards as a flooring directly sounds good, but seems not to be a common method and I am not sure why?