I'm sure the issue was brought up because of the Gold-Rush in the lines. You can search the forum for some of the discussions regarding Gold-Rush, and make up your own mind. I think that if you want to research, ask regarding indidvidual dogs as opposed to asking about an entire line or kennel. You will sometimes get "one offs", a dog who dies young of hemangio but whose pedigree has a lot of longevity behind it.
When I am checking longevity, I check the vertical pedigree as it gives information on siblings.
Unfortunately, as was mentioned above, there are still an awful lot of holes in pedigrees regarding COD and DOD
