just received the A7R II and I guess this might be geared towards anyone with A7 series. I noticed that I'm getting far better results with rawtherapee vs using adobe lightroom or photoshop for initial conversion in regard to high ISO. I do have more testing I want to do against skin and high ISO, but so far, I think I can use the native ISO 102,400 if I downsize it to 24MP equivalent from 42MP as B&W. I feel like color gets muddy, but that could be because I'm not spending too much time fine tuning to get the best results. The external link will get you to my flickr page, but if you want to see the full res jpeg, let me know.
ISO 51,200
ISO.51200 by Mark Lee, on Flickr
ISO 102,400
ISO.102400.24MP.downsized by Mark Lee, on Flickr