This was a good thread. Some thoughts:-
It may turn out that Kingman is best suited to 7f, there was never any reason to believe he'd get past a mile. At the time of the Greenham Gosden's horses were running 7lb better than anyone else's, maybe the others caught up some of that. I've no doubt he's a very good horse but probably not exceptional: but he may prove he is over 7f or shorter.The winner won fairly and squarely as far as I can see. He ran further than any other horse but still won.
As regards Night of Thunder's pedigree, well he has plenty of ingredients that say he might stay 12f. Dubawi didn't win over farther than 8f and was by a horse who didn't stay farther than 10f. Night of Thunder is fast enough to win over a mile we know, but he may be too fast to get 12f. I can't help feeling that whereas Night of Thunder might possibly get the Derby distance that Australia will finish in front of him because he'll be better suited by the extra half-mile.
The 2000G is such a good trial for the Derby because it is almost certainly the best race run before the Derby. The idea that you wouldn't consider going from 8f to 12f is a relatively modern view and anyway statistically is hard to support when half of the last 6 Derby winners did just that. Going back to 1967 (which was when I first got really interested in racing) then you have had 13 of the 47 Derby winners that either won or ran solid trials in the 2000G. [Royal Palace, Sir Ivor, Nijinsky, Mill Reef, Roberto, Grundy, The Minstrel, Nashwan, Generous, Sir Percy, New Approach, Sea the Stars and Camelot: and I think most people would agree there are more good than average Derby winners in that lot]. There was a hiatus between 1991 and 2006 but that may be just one of those things. The Dante is definitely the leading trial in England today (although hasn't produced a Dante + Derby winner since 2007), but at times the Chester Vase has been popular. The Derrinstown is a good trial and it seemed de rigeur to win it 2000-2002 but has not fared so well lately.
I think the 2000G has given us 2 horses who may be sent to Epsom with great chances and will prove itself a great trial again, but it may not have shown us the winner.