Personally, the large blotchy color left behind after your regular color noise reduction is what bugs me the most. There is very little that can clean that up nicely. If Adobe could fix their RAW engine to NOT produce that in the first place, then one of my biggest complaints about Canon RAW images would be gone. They still wouldn't have the dynamic range, but, at least the data would be cleaner. I don't really want to spend the couple hundred bucks on C1 Pro, as it's workflow doesn't seem as nice to me as Lightrooms, and it has a limited range of DSLR compatibility...but I may jut do that for the IQ.
I know exactly what you mean, this was the issue i had with the A7 at high ISO. I'm not sure I saw anything like that in the 7D2 samples I played with but I'd need to check again. Do you see this on the 5D3 as well or just 7D2 samples?
I see it in every Canon file once I start lifting the shadows enough. It usually doesn't take much, a stop and a half. It's pretty bad with the 5D III, it seems milder with the 7D II. I think Canon may have moved to their newer fabs for the 7D II sensor. If Roger Clark is right about the dark current, and if the Q.E. really is 59%, then this is the first sensor from Canon in a long while that is starting to rival Exmor as far as dark current levels go. If Roger is right, it may even be a little better in terms of dark current than an Exmor.
If the color blotch problem is a consequence of the RAW engine, then Canon has certainly made some strides. They eliminated vertical banding and gained a little bit of horizontal banding (but it is soft, so, not nearly as intrusive as what the 5D III has), lowered dark current, and increased Q.E. Read noise is introduced by the readout pipeline, probably primarily by the ADC units Canon uses. So, that is probably something they could fix (basically, anything that reduces ADC frequency should help.)
I am pretty amazed at how clean the NX1 files are though. Very clean, very neutral random noise, much lower than Canon's. I am hoping Chipworks tears apart both sensors and gives us a detailed look at the designs. I'd love to see what's changed at a low level in Canon's sensor, and what Samsung has done with theirs.
Ah, ok, I thought you meant you were seeing blotchy colors just when using high ISO, I've definitely seen the blotchy colors in the 5D3 files when doing 5+ stop pushes with dual ISO. As for the horizontal banding in the 7D2, do you have any examples? I have yet to see any banding at all in the 7D2. Here
is a comparison of the 7D2 and A7R both pushed 5 at ISO 100 from the DPReview low light sample gallery. I don't see any more banding in the 7D2 than the A7R, which is to say none.