Since those common ancestors are far back in the pedigree, if you bred an import to a "typical" No American bitch, the COI would drop dramatically. However, that very low COI will also mean that the results could be highly unpredictable in many respects. This might mean that hips, elbows, etc. might be "off the wall" ... either good, if you get lucky; or not so good if you don't have the stars align for you.
So the history of similar successful ancestory along with the potential perceived benefit of outcross genes, seemed attractive to me. However, the UK dogs generally have a large COI number. Many are in the 25% to 35% range. Is it beneficial to breed a closely line bred bitch to an even closer line bred male even though they are of different lines? I don't know. Haven't taken the genetics classes yet.