Pavel, Thanks for providing these samples! As you may have seen, I processed some crops from your RAWs and used them to start a discussion over in the DPR forum as well as on my blog. I assumed that by sharing the RAWs for download you would be okay with this, but if you want me to pull them down, just let me know. I of course credited you and this site for the files.
One thing that concerns me is that the GRD2 high ISO noise seems to me to have a "blotchy" quality. It makes me wonder whether Ricoh is applying more NR (and sharpening) to the RAW files with the GRD2.
For example, I took crops from the areas highlighted in yellow:
All the following crops are from RAW and processed with NR and sharpening settings at the minimum amount possible with the designated RAW processing application. No resizing.