We have a real variety. Full season beans can run 70 bu. average, and some of the varieties can get waist high or better and then are terrible wet when we cut them. This year was real wet when the beans were growing and made a lot of stalk. I cut some this fall that I would guess the straw coming out the back of the machine was 50% moisture. These are the beans where 20' seems like enough. We also grow quite a few double crop beans after barley. These beans will grow about knee high, yield 40-50 bu. and tend to dry down much better. The double crop beans I could handle a 25 or 30 footer no problem, as it is I am routinley running 5 to 6 mph. Basicly as fast as I can go and do a clean job. A 25' head would really be a nice size for me, but the 20 footers paid for!