First of all, I don't trust ANYTHING dpr says. I'm not saying they are wrong in this case I just don't trust anything they say because they have been proved very wrong in cases.Now, who says that ACR does not apply any NR even when the NR sliders are set to zero? Could you state your source? Reading some of Mr. Schewe's comments in this forum gives me the impression that it does (during demosaicing). I might be misinterpreting his comments but if I were you I would double check before making the comments you did.
No. If you're not using a lens that has been calibrated to the camera (i.e. a Nikon body with the 14-24mm lens; or a Canon lens like the17-40mm with the Canon 5D), then DXO is not worthwhile, IMHO. OTOH, when you have a lens and body that has been profiled, the results are fantastic!