Re: New Scrambler???
My wife has the 400, and its perfect. I cant see there being any maintenance, other than a regular tune up, and maybe having the oil pump adjusted. Its taken some descent abuse, and loved it. Its so mild, I dont think you have to worry about it burning up adn needing frequent rebuilds.
The 500 has more torque down low, and the 400 is faster on top. I'd say its probably better to have the torque, but I doubt its that much different to justify the addional cost.