[rugbymarine]

From my experience (mostly post-war vintage), a PSA 8 in an old slab will outpace a PSA 7 in a new slab. That same card will almost always fall shy of a PSA 8 in new holder, provided that the new holder is actually a newly graded card, and not a re-holdered card from 20 years ago.

But given that, I'd will always prefer to buy the really nice, newly graded PSA 7 at a premium instead of the old PSA 8 of the same card, even if that old PSA 8 is discounted because of the age of the slab. And in a lot of cases, I've found great PSA 5s and 6s using the same logic. There have been other cases where I'm willing to pay a PSA 8 price for a really nice PSA 7, especially for an example that I think is much nicer than what I typically see when browsing for cards.