I have been using a stihl trimmer with a three prong brush cutting blade. It works fine on small saplings and tall weeds but it is not very effective with grass. I have been looking at a Redmax trimmer and noticed that they also carry a recipricator. What is the difference between a recipricator and just adding a multi tooth blade to trimmer? Redmax says they are good around road trash, rocks, trees. HYPE? Anygood for whipping grass?