Just go with the gut and get the best deal you can. Warranty is also important. There isn't a massive difference between the 500s and 600s...and for that matter the 800s so don't worry about size. Besides, in the history of ATV buying, less then .3% people that bought the biggest they could wish they had bought a smaller one.. where over 80% that bought a smaller one.. wished they had bought a larger one...or at least one with more power. Think of your needs 3-5 years from now.