The underwater samples that I have found have all been shot on prores. The out of water RAW samples I have found have been posted by people who honestly admit they are not really experienced colour graders. I think it would be nice to see what the camera can produce in the hands of experts.
What si missing from this discussion for me is the 2k RAW footage from the Blackmagic Pocket Camera. From the samples I have seen I think it looks nicer than 4k. I would love to see some well graded underwater footage from it but can't find any.
I too am into deep wrecks. In my case in the Med and I am interested in both stills and video and I like ambient light whenever possible so the A7s looks very interesting. But I think 2k RAW video would be a lot more interesting than the 4k and I am wondering if the compressed Sony RAW stills would be a problem underwater. Apparently it's no problem on land but shooting underwater might reach its limits. Has anyone tried?