Still looking for stalk rolls for my 612c. Several mentioned the Calmers. Looking at their website they look interesting but they are pricey. They are having a 20% off sale now. My questions are do they require more HP? Is there any (dis)advantage if you are baling stalks? They claim can run head slower reducing butt shelling? Also, smaller residue pieces speeds decomposition? Are there any advantages to their grass/vine knives? Thanks.