No one seems to be giving this issue the time of day ..so I thought I might be direct. LR alters your original DNGs even when referenced without moving.
My workflow is pretty conservative . I import to a folder structure under Mac OS and maintain backups of this folder structure. This is completely independent of LR or any other software.
When I import the folders to LR ...I specify reference the files without moving.
After a few days posting to both adobe and the usual forums....I understand that LR posts the sidecar information (normally contained in a .xmp file) directly into your original . There appears to be no doubt that it has altered your DNG that you assumed was safe. The recommendations I received indicated that to preserve the original out of the camera ..you have to back it up independent of LR.
To make matters worse it appears that if you specified compressed DNG you just developed your original and baked in the profile . This kills taking the same file into C1 because it will not view it as an original raw and will not apply the camera profile. I have not done this .
The other issue for those of you using LR as your DAM system and exporting from LR the selects for reprocessing ..you will get the stuffed DNG . My tests show this works OK into C1 but others are stating on the LUF that the files are cooked.
Can this really be new information after more than 2 years of LR processing?