I agree with the big tractor on the cart, but how do you run one without a powershift?  I'd think it would get real annoying having to stop to shift every time you get to the combine, and how do you get going again in high gear after you are full?  Actually, that shouldn't be an "I'd think" but rather a statement of fact, because years ago I've run the cart with a 7520 with only a syncronized shift between 4 and 7 to work with and no way to get to hi, and while it beat the heck out of not having a cart, it still pretty much sucked.