We had 9610s, a 9650 walker and some 9650 STS's. I can't find much difference in capacity in corn. Except that the smaller clean grain elevator can't handle the volume on the 9610. I was able to go over 4mph pushing a twelve row in 230bu corn with all of them, till the elevator belt sliped. Just a week ago I harvested 76bu beans with an STS and a 30' flex, going about 3.2 mph. What does your 9600 do in beansIJ The STS wears out (rotor housing, concaves, threshing elements, etc.) a lot faster than the walker machines do. It takes more power and fuel to run it. They also tend to have a little rotor loss in corn. One advantage of the rotor is, that you can get buy without a power sucking chopper. The JD residue spreader do a nice job. For some reason the feeder house on the STS lifts higher than on any walker machine. The twelve row is the biggest capacity gainer. As the post below stated already, whatever you buy, make sure you get the heavy duty feeder reverser with the oil cooler. You might want to stay away from the 2002 TIER II engines.