Actually, nowadays, everyone apart from Canon is sitting at 13.8-15 stops of DR for their full-frame sensors. So it's Canon, not Sony, who are the odd one out.
And, yes, an extra 2-3 stops of usable DR makes a huge difference. Think of all the shots which can't be taken in a single exposure without a filter, but which can be managed with a 2- or 3-stop GND filter. That's a lot of landscapes. Now imagine a filter which can be applied anywhere in the scene, instead of being limited by horizons and unusabe where the line of transition isn't straight.
That's what you can do with 2-3 extra stops of DR. It doesn't make your photos any better, but it makes previously-impossible photos trivial.
This is a great point and the exact same thoughts I am having. However, I have yet to find a blog or website that shows this in a real world example. This would be an example of the D810 taking a photo with no filters and the 5DIII achieving the same results with a 2 stop GND filter in place. My assumption also is that this 2-3 stops is straight out of camera with no manipulation.
Does anyone know a good link / example to readily show this advantage?