If it were me I would pay attention to the MPG figures for the bikes I was looking at as well and total range. Don't know what the F800 is capable of but the F650 can get 70-90mpg and that 90mpg taking it easy could be important when you are looking for a fuel station. I guess the KLR may get 45-50mpg but check. The difference may pay extra cost of the F650 over a KLR. Yes you need to find out the worst fuel grade each bike will run on - the F800 despite high compression probably has knock sensors which I would feel safer with rather than having none. Whichever bike you buy run it for a minimum of 1 year 6000 miles to iron out niggles and your luggage etc - if you're buying a new bike you could negotiate the dealer may be willing to act as technical support if anything goes wrong?