To answer your question, which no one has addressed yet, the answer is NEVER (in corn). I am a Massey man, run a 83 MF 850 and have been courted by many Deere dealers to trade on a 9500, but I do mostly small grains and soys, no corn and as long as my situtation stays this way, I will never buy the 9500. My 850 will out do a 9500 in wheat when we run comparable walker loss. A 9500 could get the wheat through and threshed quicker, but they can't separate it and keep it from going over the walkers.In soys I do think the 9500 may have more capacity, but I can do 6 acres an hour in 50 bushel beans which is very acceptable I feel. But in corn I believe the 9500 could do at least half again as much as the 850. The Massey isn't built heavy enough for pushing hard in corn. If you are patient, they will do fine and give you an incredibly clean sample. The local elevator can tell whos corn it is by the sample, the two cleanest samples they get are from Masseys, a 850 and a 8450. As far as working on them I would take my 850 over any John Deere 6620 or 9000 series. Just try to change the unloader auger drive belt on the 6620 versus the 850. I watched a farmer take an hour on his 6620. I can change mine in less than 5 minutes. It probably comes down to what you are used to working on but I love my 850. And it is paid for too. All my custom work is profit.