I have tens of thousands of DNG files from years ago, but I leave all my current images in NEF format. Adobe seems to produce the same quality output whether DNG or NEF, but other products, Capture One for example, claim there is more information that helps them produce better output in the native NEF format. Capture One does produce a better quality image in my opinion, but I have not taken an NEF and converted a copy to DNG and looked at the output of both via Capture One to see for myself. That said I do trust their software developers if they say the NEF file allows them to produce a better baked image.

Having moved from Adobe to Aperture and now moving in to Capture One, I think it is safe to say that sticking with the original camera native raw file is the right answer for me. If one were to select Adobe and never, ever leave it, then selecting DNG would be fine.

Over the last six months I evaluated Lightroom and Capture One as the destination for all of my images that I had previously moved into Aperture. My archives include over 30,000 DNG files. Lightroom is much more consistent in handling DNG and NEF files equally. Capture One is inconsistent with DNG files in that DNG files from some camera models produce stellar results in Capture One while DNG files from other camera models require significantly more effort to get right and simply don't compare to what Adobe can do with the same DNG files. Adobe seems to be able to produce the same output from DNG and NEF alike. Capture One not so much.

I have to hand it to PhaseOne who produces Capture One. They have listened to me and have looked at sample image files I have shared with them and they agree they can do a better job and are committed to improving their DNG file format support. Having shown them that Aperture handled DNG files just as well as it handled NEF files has convinced them they can do better. I look forward to future enhancements to Capture One for DNG raw file support.

The point of all this is to re-enforce my earlier statement that DNG support is very much NOT universal, and even image processing software that claims to support it may not support it as well as Adobe supports it. For that reason I feel that the camera native raw file is still the best file format to retain and process in all software. Maintaining the ITPC metadata in the sidecar XMP files is universal. Other aspects of metadata like ratings and labels is less consistent, partly because different tools offer different labels.

The most significant benefit to Adobe's DNG file format is that it contains all of the raw image data, all of the metadata you apply to the image, and optionally a copy of the original camera native raw file. It is a single container holding all of the information associated with an image so you don't risk losing metadata in sidecar XMP files. DNG would be enormously attractive if all software makers provided the quality of support that Adobe provides. That is not the case. Software makers invest in decoding camera native raw files and see little to no benefit in also investing in decoding DNG raw files. The one exception most make is for cameras that produce DNG as their native camera raw file format such as Pentax and Leica.