I don't know about the M6800, but I've owned a 8540 and 9540, presently own a 105 and 108. They all ride rough because of the short wheel base IMO. I grew up on the JD 3010, 4020, 4320, and 4430. These long, heavy JD's ride much better, but I don't have time to work on them. The Kubota's are...