Thanks for that info, Miles. It looks like the XF650 might be a good buy.
What are the racks and panniers on your bike?
Did your bike come with an owners manual - if so does it say what Suzuki reckons to be the maximum payload? The handbook for my Suzuki DL650, for example, has the dry weight (197kg) listed in Specification at the back of the book and the Gross Vehicle Mass (420kg) under Loading Limit on the second page. That gives me 223kg for fuel, oil, coolant, rider, pillion, accessories and luggage. I am hoping the XF650 will carry about the same.