that thread is on a fred miranda review using canon lenses on an a7r for landscapes.
thanks I saw that article. that is why I am considering the Sony A7R. Which is the better way to go? Waiting for Canon may be a long time and if a body comes out it will be expensive.
It seems you can't readily attach Canon lenses to Nikon bodies, for the reasons given here:http://photo.net/nikon-camera-forum/00Uw1k
So if you're deciding between a Sony or Nikon body, the answer seems pretty clear - get the Sony, which also gives you the usual advantages of mirrorless bodies & EVFs.
Of course, as others have pointed out, whether you'll find the A7r gives you better results depends on how you use/view the results and what your criteria are - the extra resolution and dynamic range may or may not make a difference to you; and bear in mind that while you will almost certainly get better center resolution if you attach a Canon lens, that may not be true of corners:http://www.lensrentals.com/blog/2013/12/sony-a7r-a-rising-tide-lifts-all-the-boats
My hunch, after playing with an A7r for a couple of weeks (and an A7 before that), is that Canon lenses (the ones I tried, anyway) yield slightly better results on A7 bodies than they do on a 6D or 5DIII (though of course they're easier to use on the latter), that the difference isn't just a matter of extra resolution (if you like viewing images 1:1 on a good, big monitor, the results certainly have an extra "wow"factor, even if you don't use a tripod), but that the 6D is probably better at high ISOs, at least in terms of noise.
But I've not done anything approaching scientific tests, which is why I say "hunch" (I imagine there are useful A-B comparisons of the same thing shot with the same lens on different bodies on-line or, if not, that there soon will be). If you're in a position to rent, why don't you rent an A7R & metabones Canon-E adapter and find out first-hand if you notice an improvement that's significant to you? (And don't just try it on landscapes, unless that's all you photograph.)