I'd be more concerned about wrecking the combine than the head! Ditches, holes, bumps, and etc. eventually take there toll. But then, if you have uneven ground and_or terraces, eventually you will wreck the head too. Get an 8 row head. You will still be running 6 mph in 140 bu. corn. Fast enough for me. I'd like to go to a 12 and slow down a little.