The Challenger 670 is under powered and has a very poor cleaning shoe. Agco refuses to invest money in harvesting technolgy. It is basically the same design as the old White combine. Depending on crops, you may need to reconfigure the rotor, what a hasle, if you do that, you should buy a CIH 2388. The lexion on the other hand will cost more, but will harvest 25% more than a Challenger. In addition it is easy to change from crop to crop with this machine.