A stop or two of DR or noise isn't going to be the difference between paying your bills or going broke, but to say it doesn't matter because it won't show up in print is ridiculous. The more latitude you have in your files, the greater the potential to save you time in the field and deliver a better product after the post production process.
+1 .... which is why I keep the iso as low as possible and why I have become a flash fanatic
You guys are missing my point. Assuming the worst case scenario, the 5D III hasn't changed. Its not better, but it also isn't worse. Millions of photographers have used the 5D II as well as cameras with much worse read noise and the same DR as offered by Canon cameras for years, and its never been a problem. Look at read noise levels for digital MF cameras, touted as offering FAR better quality than any lesser camera by professionals who use them every day for publication work. Digital MF has relatively poor QE (15-25%), high to very high read noise (15-30 electrons), limited maximum saturation relative to the likes of any current Canon or Nikon/Sony (less than half as much in more cases than not), and they all top out at around 11.5 stops of DR or less.
The Leica M9, also considered one of the best professional grade cameras on the market, has consistent read noise of about 15.5 e-, maximum saturation at lowest ISO of 30000, and maximum DR of 11.1 stops. There have been reports of banding issues with several Leica sensor designs as far back as the M7, and the M8 had particularly bad banding...but it was still considered a better camera than anything from Canon or Nikon...since banding only ever exhibited in shadows, and was relatively easily mitigated in post.
You can make the argument that better DR may make your life easier. If you regularly find yourself dragging up the shadows, then you might as well jump ship and head over to Nikon where the grass is greener. Or you could ETTR, utilize the sensor DR better (Canon does seem to have a bit more highlight headroom than Nikon by about 1/2 a stop based on DPR charts), and correct exposure at the click of a button in post (or, in the case of LR, you could simply set a negative exposure bias in the default import profile for your cameras, and never actually have to worry about it again...no time wasted whatsoever.) But the simple fact of the matter is the cameras that are literally considered THE BEST on the market by most professionals who shoot for print and publication on a daily basis, the likes of Hasselblad, Phase One, Aptus, etc. are no better or worse than anything Canon is or has been putting out. Actually, with the 1D IV, 7D, and 5D II/III, Canon is better on a technical level...although we all know that still doesn't matter a wit when it comes to producing good photographs.