I've had my Agri-Fab spreader for almost three years and its worked fine for my application. Mine is a tow-behind 125 lb. model. I only use it to spread pelleted lime and lawn fert. 3 times a year. No problem with binding gears. I also have a 600 lb. Sitrex for the back of the tractor that is PTO driven and is used to put pelleted fert on the pastures. I looked at the $675.00 pull-behind from TSC but, for me, it didn't make sense. Here's the three things that pushed me toward the PTO driven unit:
Price. I paid $299 for my Sitrex, new. The pull-behind would have been twice the cost. More moving parts, more cash moving out.
With a ground driven unit, you're only spreading when you're moving. This means that if you need to get into a tight spot, or can't move very fast, you're not going to effectively throw whatever you're spreading. With a PTO unit, I can spread even if the tractor isn't moving. On the pull-behind, part of this is also weight. The less sfuff you have in the spreader, the lighter it is, and the lower the grip between the wheel and ground. Basically, it works less efficiently as the contents are emptied.
With a PTO unit, I can adjust the height and pitch of the spreader to help extend or restrict the distance of the throw. Can't do that easily with a pull-behind.
For me, the Agri-Fab works well for it's use, but if you go larger, get a 3pt. PTO driven unit if you have the tractor to mount it on.
MFL