eumenius beat me to it! I just looked at his link and it is the actual Jobo page listing the differences between rotation speeds between old and new processors. (Thanks, eumenius. I'm going to save that because Jobo is taking more and more stuff down from their website.) As you can see, the newer machines do not increase in rotation speed after the 4 setting. They increase slightly from the 3 to 4 setting which is what I found with my machine. And consistent with Jobo's data, I found that I achieve 50 RPM when my speed control is set slightly over the "F" setting. It's nice to know that my new machine isn't defective.

Thanks everyone.