Dieter:
I have not been to Ellerston, so I cannot comment on it directly.
However, there are quite a few courses now which appear in one ranking or another, where the only way the panelists are able to play the course is as a "special guest" of the owner. In the States, Shadow Creek was once the poster child for this; now that it's got its ranking, anyone can pay $500 to play it. Places as diverse as Rich Harvest Farms and Wolf Point are in the same category. And, with all of them, there is some suspicion that those lucky enough to be invited might either
(a) overvalue a place that they got to play and you can't, or
(b) be unwilling to show "bad manners" and downgrade a course where they were lucky enough to be invited.
It's also true that projects like Ellerston are unusual, in that the architect can design things that would be impractical at a regular course because of traffic issues / speed of play / etc. In some ways, that's very cool, but it's also understandable that courses which have to rely on customers for their survival might think it's all a bit unfair.
Also, I was at Barnbougle just the other day and they had no inkling this ranking was coming, though I'm sure it's welcome news for them. It amazes me that the Australian golf market is so price-sensitive that Barnbougle still can't charge more than $100 per round. The professional remarked to me that if you wanted to make a week's trip, an American could choose to go to Barnbougle over Bandon Dunes and wind up paying much less for the week, even with the large airfare difference.