What size Echo did you bend the shaft on? for what you are doing it sounds like you should be running an SRM 3800 or SRM 400 Echo Brushcutter.
If it is an initial clean up, an FS 250 Bike unit will work fine.
If you are going to do this every year and maybe hire the neighbor kid to do it for you, I would look into a clearing saw. It is a heavy duty brushcutter with a larger drive shaft, out tube and gear box. For example, one attachment for them is a christmas tree harvester attachment. They are designed to cut up to 3" diameter stuff all day long. The smallest one STIHL makes in this classification is the FS 310.
The FS 350, FS 450 and FS 550 are all clearing saws but are way overkill for what you want to do.