DxO labs have their methods and their procedures. Some have said in the past they weighed more into their high ISO scores and now are weighing more into DR... I dont know how true any of it is... If you take it at face value, nikon has always bested canon in these tests for the last decade or there abouts... Quite frankly i'd be quite shocked if any Canon camera started testing higher than nikon in the foreseeable future, but it is what it is. Personally i take all these tests into consideration when it comes into purchasing decisions, but I weigh most my decisions on my eye test and usability. I had no issues whatsoever with the 5d2 sensor, but it's handling never sat well with me so i opted for the 7D for the longest time because I knew I could always get the shot with the 7D over the 5d2. IQ on the 7D was marginally acceptable to it worked for me and my clients have always praised my work. I dont need 14 stops of DR to make my clients happy nor do I wish to undertake extra post processing just to get extra pop. In the end, the 5d3 is the best of both worlds for me... Yes there are room to improve, there always is, but as long as the camera doesn't slow me down, i'm cool.