Went from an F2 to a R40 about three years ago. One of the best decisions I have made. Run a 4-36" hugger corn head and a 18' bean head. Finished hyper mods last winter except I put a Sunnybrook Gen 1 rotor in because they had special on them. With the mods in 150 bushel corn the limiting factor was the speed of the corn head and not the capacity of the combine. Same in beans. Only problem with a 4 row head if you have hills the backend will slip down the hill and the spreader will do a nasty job on the standing row of corn down the hill.