Cooperation between TPGs would not make a good business model. A given TGP wants a collector to collect their slabs only, not a competitors. Slab collectors often crack coins out and resubmit to keep all the slabs in their collection from the same TPG, and doesn't the fure fly if it comes back with a lower number. If NGC and PCGS operated different grading scales there would be fierce competition to set the industry standard, but that isn't the case. The world of numismatics now has an accepted grading scale and the horse has bolted for CGS. They've scaled back their operation and no longer grade a significant number of coins. Even the separate section in London Coins auction (the same business, effectively) has been dropped. I do think it's a shame because I believe we need a UK grading house. Despite the huge reservations of many (to an extent, myself included), the TPG market is here to stay. Heritage's newsletter, sent out yesterday, trumpets their biggest single week of numismatic sales $105 million. That is serious money - $105,000,000 in just one week! Virtually all of those coins were slabbed. Whether we like it or not, we can't ignore it. Here's a link to their newsletter.