Very good post, and I agree with much of what you say except that you make it sound like Ducks are only moving up now, and I would say they've been skyrocketing for around 3-4 years now. It's definitely not a recent phenomenon.
From my own perspective, the world changed around that time period when some gorgeous 9.4 FCs came up on eBay. I had already set aside some space in my collection to slot those beauties because I'd had the field all to myself for the few years and couldn't imagine that I wouldn't win the books. Then I got blindsided by some Scandinavian arrivistes. Then Gambaccini started auctioning off more gorgeous FCs and WDCSs on eBay and the pockets of the winners (mostly Scandinavians, but some Americans as they started to raise their game) seemed to be limitless. And it really hasn't stopped since.
Yeah I was watching the heritage/ebay auctions last year with all the high grade WDCSs. I was interested in several of them but they all closed for at least double the current grade value at the time. Some were triple or even higher. It was crazy but it shows that there are some serious buyers out there for high grade WDCSs.