I got my MX 6 last fall. I've only put about 15 hours of mowing on it but so far so good. Not been able to break the output shaft despite my very best efforts, such as hitting a unknown 8"x6" stump of a pine tree.....cut it right off.

Mine is the Mexican made one with the Chinese made gearbox. The one with the issues are the Canadian made ones with the Spanish gearbox. Output shaft seems to be brittle and would break.
The new MX 6 mowers have a 5 year warrenty just like the other mower brands, so Deere, at least, think they have solved the gearbox issue.
Mowed with mine today. I've got the chains on and that prevents some airflow under the mower. It leaves some grass clumps but mows very very smooth. Just like a finishing mower. High blade speed on them. JD says the skids are replacable. You just grind off the old skid and weld on a new one! <~~~~~yeah they really say that in the owner's manual.:confused2: It has a light duty catagory 2 pto shaft. Easy to handle and attatch to the tractor. I think that the money there are better mowers out there, if I had to do it over again I would get a bushhog 296.....but I'm happy mowing with my MX 6 and think you would be also. I traded mower in for mine but the price was about $2650. Just checked the gearbox rating. The older Spanish boxes were rated to 54 hp peak and 61 continuous. The newer Chinese boxes are rate 75 and 90 continuous. Quite a bit stronger. Welds and craftsmanship on my Mexican made MX 6 seem very good. Paint is excellent. So hats off to the Chinese and the Mexican workers for JD. Man...typing this has made me hungery for some reason...........:licking: