I ran a Kershaw built rotary that had twin spindles and the swinging blades that were one inch thick. It would easily take down an 8" tree with a lot of noise and some vibration. You could change the direction the spindles rotated, so it was nice that you could have some control of the direction of the projectiles. That thing was scarey. The problem was, that after a while all the steel and welds start to crack from the impact. I would stay away from the big stuff, it will cost you sooner or later.