Yes, when you click Metadata/Read Metadata From File LR will load all your edits from the XMP. However, not all the organizational stuff you might have had in the old catalog, like collections, flags, etc., is in the XMP.
I rely on my backup system (Time Machine in my case) safely backing up everything all the time, and never back up my LR catalog as a separate action. A, I wrong to do this?
well i did try to do this with 2 files.they are raw files with the XMP files with them, and when importing into a new LR it seems LR automatically keeps all changes made to the file.
but the images marking is important, like color labels and flags. just stuff the relates to a specific file,is there any way to extract this info (color labels and flags) from the XMP sidecar file?