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My answer is based mostly on inexperience, as the only raw (DNG) files that I have worked with were from a Leica M8 demo, but it seemed to me that some of the controls, e.g. colour temperature, highlight/shadow recovery, in raw conversions programs (Photoshop, i.e. presumably ACR, and a demo version of Aperture) were much more powerful and easier to use than trying to achieve the same effects in Photoshop when working on a tiff file (e.g. Curves).
Tiff is good to work with but the metadata and other changes you make are in a sidecar text file. When archiving, that needs to be associated with it. If not, you lose the good stuff. Or better still, archive in DNG because there is no sidecar attachment, it is in the DNG. TIFF for manipulation if you wish, DNG for archiving (although you can manipulate in DNG as well). With my Leica files, I never leave DNG (in Lightroom) except if I want a fine print. It then goes to TIFF, and then to Colorburst for printing.