(with apologies to Franz Kafka:)
Sony: "We just made the finest 35mm image sensor in the world today"
Me: "Great!"
Sony: "Ok! You can have images that look just like images from the finest 35mm image sensor in the world today"
Me: "I thought you were going to give me the finest 35mm image sensor in the world?"
Sony: "We totally are...well, we're giving you the next best thing, and you totally can't tell the difference!"
Me: "But...but..."
Sony: "Well, we can't exactly let you use the highest quality setting on the finest 35mm image sensor in the world..."
Me: "But...but..."
Sony: "then you might not think that there was something left that you hadn't tried"
I hear you Luke, and I think it makes good marketing sense for Sony to put all fears to bed by providing a lossless compressed mode as well (expect some possible compromises if they do, though, e.g. slower FPS).
But on a practical note, since I seem to recall that we share a fondness for Jazz, I remember participating in A/B listening tests with audio equipment more expensive than a car by like minded supposedly golden eared folks when MP3 was starting to enter the mainstream. With well encoded material some could hear differences at 128k bps, a few could on very specific rare passages at 192k (top hats come to mind), by 320k nobody (nobody) had a clue as to whether the original master or the compressed version was playing.
I can't speak for the delta thing, but since in 10+ years nobody that I am aware of has been able to show loss of visual information with 12/14-bit captured raw data 'gamma' coded to 10/12-bits in Nikon's 'lossy' NEF compression - the only type of raw file available to many Nikon cameras today including, I believe, the new and outstanding D5500 - I think we are probably talking the visual equivalent of 320kbps audio: nobody can see that the file is smaller, even after aggressive PP. The data may be different, but the underlying visual information recorded is the same in both file formats.
I am interested in this subject, so I would be happy to be disproved if evidence is shown to the contrary. Anyone?
Jack
PS BTW, the parallel with audio breaks down because there they actually do throw away recorded audio information on the basis that humans cannot hear it. The digital photography case for raw data 'gamma' compression is much stronger because here they are simply not using up bits for stuff that the camera cannot record. Take a look at the market balance example
here for an idea of what's happening.