I currently own a 600/650 TA outfit and a kle500b6,
The kle is definitely more of a "budget" bike, but was certainly good value. (£2500 with 139 miles on the clock). Tappets are a bit of a faff, involving dropping the coolant, new orings for the pipes etc, but more time consuming than difficult. The engine doesn't have anything like the grunt of the honda, but is fine enough for a farily lightweight machine.
Best thing is the running costs are really low, it will eat pads, but only one set to buy. I get 55mpg with mixed riding. 4500 miles from the rear trailmax.
Keep the brakes well serviced, as they are a bit feeble, and keep on top of corrosion, the paint and other finishes are a bit thin.
The exhaust wont last either. Need to find a stainless replacement, that wont affect the jetting.
The most effective way of turning petrol into noise without the side-effect of horsepower