They brought it out because it was spec'd exactly the way I wanted it....and I could not wait any longer

Would I have liked a better price? Yes....but a few hundred USD are not a major issue, and I blame that more on the weak $, not, so much, Canon.
Greater DR at low ISO? Maybe..? But more as insurance against my not getting the correct exposure. While intellectually it may seem nice to open up all the dark shadows, an image like that usually looks too artificial and is why we often tire of HDR....even if it is not garish.
More megapixels? Always nice, but has trade offs....which I guess is true of pretty much all the specs. It's like what we are told about tripods....if you want cheap, light, and sturdy, you can have any 2, but not all three.
In summary,I believe the 5D3 is an extremely well balanced system....and aim glad I jump on getting it right away (even if it is going to need some taping up).
John