I have the X485, that engine is butter smooth- I love it- never run out of traction with the turf- tires- actually have only used the diff lock a couple times- I mow about 2 acres, I have a ditch line down the side of the property, and one in the parkway, I guess fourwheel drive would be nice if I wanted to destroy the grass and mow mud but unless you have REALLY BIG hills, or massive snow moving needs- four wheel drive is not needed- kinda like all the soccer moms around me who drive Hummer H2's-