A friend of mine has a 9650STS, and I have a 2388, but we've never run side by side. I've ridden with him and he with me, and we both are of the opinion they are about the same capacity, at least in soybeans. We seem to run about the same speed and cover a similar number of acres in a day. I was cutting rice about a half MPH faster than him this year. His doesn't seem to like green crops very much. I don't know what it will do in wheat because he doesn't grow any. Since you're already used to the IH design, I would recommend the 2388 because of the simplicity and state of refinement. CaseIH has had 25 years to work out the bugs on the 2388, while JD has had about 3 to work out their design. Just my 2 cents.