SuperS, we could debate this subject endlessly, I choose not to, but I would take my chances on 6.5x47 simple because of reading about easy tuning and small groups ever since the cartridge came out.
I was there right in front of the target at 1000Y in the pit at the range near Tucson AZ when Charles Greer, with his 300WSM set his 3.9??? something inch group, I can't remember exactly what size it was, just that it was a record. I watched it appear in front of my eyes. It's the only firearm benchrest match I've shot in. Cool huh!
I agree, to a point, at any match there's a element of luck as to who gets the W. Maybe David with his 6.5x47 got the best bench location, the least wind, and his bench manners were flawless??? However you slice it, a W is a W and I'm not saying that the top cartridges aren't capable of winning at any given time.
BTW, I'm not having good luck trying to talk myself out of 6mmBRA for my next barrel. Maybe even a 25 BRA! What do "we" think of that, LOL.