EDIT 16/01/2015: New or changed content
PROPRIETY VS DNG
The last time I was reading up on the subject there were a ton of products that supported DNG from more than 200 companies, plus Adobe is not the only software house to offer a DNG converter so DNG is looking very promising. In the mean time kudos to Leica and Pentax for as far as I know, they are the only camera companies offering DNG raw files. Wish more manufacturers would do the same - Fujifilm, are you reading this?
• 30,000 x 22MB = 630GB
• 30,000 x 4MB = 110GB
MY DNG WORKFLOW
Another big advantage of DNG, apart from size, is that I no longer need to worry about loosing those XMP files that need to tag along my RAW files. All my processing, GPS coordinates and keywords are stored within the DNG format. Plus the conversion is so easy to do in Lightroom. Once I have selected the files I want to convert, I go to Library>Convert Photo to DNG and choose the settings I want and then go make a coffee while my computer starts work.
Below is a screen grab of my settings with the most important being "Embed Fast Load Data" and "Use Lossy Compression".
So your first question is why do so many people insist there is. Well, technically there is a difference its just that you cant see it. During the compression a lot of data has been thrown out, this can be seen on the histogram as you switch from the DNG to the RAF file. Most of you wont be able to see the difference simply because most monitors are 6 or 8 bit. Some professionals with an expensive 10 bit calibrated EIZO screen may see a slight difference in the highlights, but believe me, it will be such a small difference that it makes the large saving really worthwhile!
Also I'm very confident that any future software will be able to handle today's DNG files and I’m sure most of you will agree that the same can’t be said for any of today’s propriety RAW formats.