I'm pleased to see so many folks here working on this to the betterment of everyone else -- we have some knowledgeable people and this helps. I have posted a number of videos on the P4P and been amazed the the range of comments I get. One of the ones that I've seen a number of times in the last few days is that with D-log you are supposed to over expose a bit. Of course, with 8 bit the DR is going to be on the low side so exposing to prevent the sky from blowing out at all would mean the mid tones and shadow detail would crush to black so with 8 bit you have to sacrifice a bit of highlight detail so that you can bring up the mids and shadows. If you have something more like 14 bits then you have more headroom to expose for the sky and then bring up the mids and shadow.
One other thing that's been commented on and I've seen this a number of times is that to counter banding you need to use a slow shutter speed. The mechanism for this isn't entirely obvious but it would appear that adding a little blurring can help with banding -- anyone care to comment on this?
I think when they say you should overexpose, we may understand overexpose the underexposed (It's kind of weird I admit lol).
After reading that about slog-2 from sony (Exposing and Using S-Log2 on the Sony A7s. Part One: Gamma and Exposure.), the correct exposure level for the white are at 59%.
Let's say DLog is quite similar to this (maybe, maybe not, but let's say it), if we use the correct exposure, let's put the white at 59% (the underxposed). To get less noise in the shadows, we can overexpose (the underexposed) by maybe one stop, at around 71%
For the banding, I think (but it's just a supposition, I'm not sure of nothing there) that we are overexposing the DLog way too much (like if we were using None or DCinelike) and the values near the white are more compressed than if we had shot with the whites lower (less compressed in the middle). To test that, just do the same test, but at different exposure and look if there is still banding in the sky.