There is little to choose between the bikes as such, but if you are going to ride far, the simple air-cooled Diversion is best, I feel. Very easy to service, whereas the GPZ has the extra worry of water cooling, pumps and plumbing, and, if I remember correctly, you have to change the coolant just to service the valves. ( If you are really split, check this as I may be wrong ).
The KLE has the same GPZ500 engine. I wouldn't worry about the fuel figures you read in mags, as journalists ( especially British ones ) are loathe to admit they didn't thrash the bike " knee down this, knee down that " on test. Swift but gentle throttle use should give you at least 60 m.p.g ( 90 kilom to 4.5 litres ) AT LEAST.
Keep the speed around 65 mph/100kmh and cruise and you are looking at 70+.
Your choice, but I'd go for the Divvy!