I DONT EVEN KNOW WHERE TO BEGIN!
Sure, allowing ICG coins into the registry would make a more inclusive registry. But what exactly are we including? They do not grade consistently or accurately. I have handled 3 accurately graded ICG slabs. ICG grades 1-3 points above the true grade on a regular basis, and watch closely for problem coins...graffiti, rim damage, etc., because they aren't very good at spotting such things. There is a reason, regardless of grey sheet charts, why ICG slabs sell for a fraction of NGC and PCGS prices. They simply are not a comparable product.