I guess some of that quantitative chemistry from years ago pays off. I started with 1 lb 6 1/2 oz roasted Jamaican Grade I nibs, a 3 1/4 ounce plastic bowl and I used 5 oz melted cocoa butter to flush the system. I ran the waste through 3 times until only a tsp was left. Then I ran the cocoa butter through. So I started with 1lb 14 3/4 oz total and ended with 1lb 13 1/2 oz. I lost only 1 1/4 ounces to the champion!!
So that tells me that John sent me relatively pure nibs and that my technique is pretty efficient. Incidentally, I have the industrial strength Champion 2000. I have no idea if that's important or not.