Actually you're half right on the spreading 40 ft. Being offset, the right side of the 36 ft. header is the same as the 40 ft model. So, if you're happy with the job it does on that side then you'd be happy with the 40 ft model.
I take it you run your guidance thru your pro 600 monitor. Who did the setup on it, you or your dealer? When you run the 36 ft. 2162 you need to program in an offset and I have a few questions on that.