I've heard great things about the Clarke Machine rolls cutting up stalks if that's what you are aiming to do. We purchased an 18 row 20" Clarke Machine head this fall. We didn't get it with the knife rolls as they won't work for us, but I can tell you that it is a much better head than a standard JD head. It is a new JD frame with 40 series units(completely rebuilt w/ new bearings, rolls, etc.) and it was less money than a 12 row from Deere. I do think though, that the Clarke Machine rolls are pretty hefty when it comes to price.