You have an excellent consultant right there the way it sounds. We have installed cover kit or made seperator grate less aggresive for several crops. It reduced crop loss in barley for I believe it prevents straw from rolling which can trap seeds. It helps reduce edible bean straw from rolling into rope in some conditions. It helps prevent grinding up sunflower heads and stalks. It helps prevent grinding up canola straw. I here it helps prevent rolling up green milo which caused rotor loss. Some guys have done this in heavy duty corn soybean areas with no problems that I've heard of. One should remember that P1s did not have this grate and I'm sure you have read about some great reports on them machines. Also keep in mind that P1s have a lot less concave and they are working great as long as helicals are set up right. I have been working at reducing aggresiveness of concave for many crops with very promissing results.