I'm also asking the same question.
In my view there is a technical definition of DR (Full well capacity/Read noise) that may be not relevant to photography. In real photography it is my understanding is that shot noise dominates and thats about square root of detected photons. The number of detected photons should be proportional to the size of the sensor. So doubling the surface of the sensor would give about half a stop, but I may oversimplify that.
In addition I feel that the discussion is complicated by the fact that we would have most noise in the dark parts and tonality would normally be compressed in the darks as we apply some kind of shadow compression (toe characteristics) in both image processing and printing.
The biggest problem IMO, is that strick measurements are not applicable in real field photography and I would like to explain why.
The scientists measurements are giving a very small advantage in DR for the MF backs, that's one part.
1/2 - 1 stop is very little, almost insignificant and at the same time important.
My personal experience of designer in some advertising adgencies during many years, I have spent time in the post production task and the differences between files are clear.
The field, is that MF gives you a lot more room
than 35mm, even an old 22mp MF. The difference is not little but huge, but only when you need to play on the extremes.
That is indeed more noticiable when you need to push or extract a lot from your file. Not only it gives you room, but the quality of this "room" is much cleaner at based isos,
specially in shadows. The result is that for certain applications and in extreme PP, MF is simply way ahead. For how much?
I mean, how much suggestives DR stops would I give to MF when it comes to the real task? In my experience I can see at least 4 stops difference in applications before the image starts to fall appart.
It's amazing what you can recuperate with these backs. (ok, I know that normally if we do the job right we shouldn't have to, but...)
Maybe it is not 6, but it is certainly not 1.
According to the focusing, (still do not understand why things are not in focus for some) you center a lot the comments on the lens, but with the resolution of the current backs, that is just a small pasrt of the equation.
Mirror is a real problem (I suspect to be the biggest issue), tripods also and the way you handle the lightning in the case of controled sources etc...
Correcting manually after re-framing.
Also, I've seen pros that often go over closing their diaph. Beleive it or not but it is more current that you may think. Shooting at f22 and then complain about the lack of sharpness quality...