I'm interested in starting to convert my photos to DNG instead of NEF, because it allows Lightroom to embed it's metadata into the actual files, and because the "fast indexing" feature makes significant performance gains on my hardware.
While considering this, I noticed that Lightroom has the option to embed the source RAW into the DNG it creates (if using DNG mode), which puzzles me. It would double the size of the file, and (in theory) the NEF and the DNG contain the same information. Is there some kind of information loss or disadvantage (other than requiring the conversion step in one's workflow) that occurs when being converted into DNG?