So, in summary: a new Canon sensor with virtually no improvement in DR and low ISO performance, even after several years of stagnation (T2i, T3i, T4i, T5i all pretty much the same) and at least a couple years being significantly behind the competition. Just another sign, IMHO, that they simply don't care much about the landscape niche and are content marketing primarily to other segments.
Preparations for switching to a D600 are underway for this Canon loyalist since the 300D. It wouldn't surprise me at all if landscapers on this side of the fence who hold out another 2-3 years for the 6D/5D3 successors are ultimately greeted with a similar fate. Based on the responses in this thread, and many similar ones here recently, the lion's share of Canon users simply don't care much about DR, regardless of how far behind the pack they fall and for how long.
I think they would be praising the DR if the shoe was on the other foot. If the Canon sensor was the clear leader in DR, we would be seeing it as one of the major benefits of Canon. Just the nature of the human beast.