I strongly disagree that ND grads are a waste of time, in fact a few months ago, I gave a talk to our local camera club in an attempt to persuade them that there is an alternative to spending hours in Photoshop. While the grad tool in LR is pretty good, it can't recover detail that isn't there. If areas of the sky have blown out, then that detail is lost. Typically, there are up to 5 stops difference between the sky and a roughly mid-tone area in the foreground. If you have significant shadow areas, then it is even more. There is no way that LR or any other RAW editor can cope with that. I often use a 2 and a 3 stop grad filter on the sky and sometimes two 3 stop filters and I sometimes still need to recover detail in LR. Without grads, it would simply be impossible, short of using HDR or some other blending technique. Not only do I not like HDR in general (although it can be a useful tool sometimes), I also don't like spending hours trying to correct something I could have done in camera, with some thought and consideration. To me, that is what photography is all about, using your skill and technique to create an artistic image (or a basic record if that is what you want/need to achieve). While I have nothing against those who want to do alot of processing work, when you start to blur the lines of reality, to my mind you are crossing over into digital art, which is fine if that is what you want, but not for me. It's really a matter of whether you want to develop/demonstrate your skill using aperture and shutterspeeds (not to mention angles and composition) or in post processing. Some will want or enjoy developing their skills in editong and processing, while others will just want to enhance an image with basic processing workflows. It depends on which of those two groups you fall, as to whether ND grads are useful.
I haven't got any comparisons, but this image demonstrates the problem. Due to the wideangle, I couldn't add grad filters, so added a gradient in LR. The clouds don't really look right though and there is a big patch that is completely blown.Tarbat Ness Rockpool
, on Flickr
In terms of whether the 5D MkIII is a landscape camera, I think with current lenses, it is the better option, as I think 36 MP is pushing the limits of most currently available lenses. While I have one or two which would be ok, I don't really want to start replacing expensive lenses because they are now producing soft images on a 36 MP body, particularly when it would be certain areas of the image. If the image was softened all over, it would be less noticeable.