This is an unusual topic and worded so that it qualifies for this area where I think I would like it qualified. As a 450x dirt biker, if you were going to buy an sport ATV for guests and as a back up vehicle and tow out vehicle, forget for a moment the attributes of the manufacturer chassis and controls involved. Strictly from engine performance and reliability basis, which would you be more comfortable with and what would be the benefits? For me I think I am leaning toward buying the Z400 so that as my guest and rescue vehicle it will always be ready with few issues and because it has 5 speeds pulse reverse and the 450x does not. I have to make up my mind before next week as I will be buying one or the other.