The Old Tyme peanut grinders work well for many bean types. However, if you have one that does not have a lot of fat in it, it does slow down.
There are machines I have seen that look like meat grinders, but have stainless steel grinding burrs that are specifically designed to handle oily nuts, seeds, and beans, including cocoa. Throughput is over 20kg/hr and the fineness is 80-100 microns. If you are interested I can look into them more closely.
Another alternative I have been looking into is vertical cutter mixers. You could probably process about 30 pounds of nib into coarse liquor in under five minutes. You can find them used for very good prices, especially for the capacity and throughput. Also, you can add sugar to the liquor to pre-refine before putting into the grinder.
clay - http://www.thechocolatelife.com/clay/