I have the Stihl FS 450. With the OEM shoulder harness it's not to bad. Used w/out this harness - it will KILL your back pretty quick. I have many different heads & blades. The best head - the one with the three free swinging nylon blades. I took one of the brand new nylon blades to the local metal shop. They made me two complete sets of high carbon steel, duplicate blades. They are heavier than nylon, cut better and looks like one set might last forever. Their operational limit - around a 2" sapling.