I didn't know Torges didn't like them either. A true farriers rasp is rough on one side and smoother cut on the other. You use one side to hog the material off a horses foot, and the other side to clean it up for the shoe. Price also depends on were it was made USA, or China. There is a huge difference in the quality of the steel. The USA one will last years longer, but will cost double. If you go to an antique store, make sure its made in USA. It will have a stamp in the steel down on the end by the tail, saying China or USA.
Chris is right, they aren't for tillering. I don't think any rasp is for tillering. You could use the less aggressive side, but you might end up with tool marks, or a bow that is too light. Justin