I too have a KFX and YFZ. The KFX has turned into the wife's quad. I will comment on the feel since no one has touched on it yet. The KFX has a much higher ride. The seat is much softer and the quad feels more top heavy. The YFZ has more of an aggressive feel. You sit much lower (which makes no reverse, no big deal...just put your feet down and push :lol ), the quad slides much easier, high siding is virtually non-existant so far, and it has a much lower tendancey to wheelie to the sky when traction is plentiful. On the other hand, it has so much power, it tends to lift the front tires a couple inches in hard riding situations, which causes a loss of turning traction on occasion. Overall, there is not one thing I would change about the YFZ except a larger fuel tank. Both share a 2.6 gallon tank, and obviously the YFZ eats fuel much faster. I could almost go a day of hard riding w/ the KFX w/o any fuel issues. The YFZ needs to be topped off after each hard ride to be safe. Another great difference is suspension and how it affects handling in whoops. Here in Florida, whoops are EVERYWHERE. I could get over about a dozen whoops at a good pace w/ the KFX before getting exhausted....I can go at least 3-4 times longer over the whoops on the YFZ w/o the fatigue.