I've recently completed the process of scanning a large number of transparencies and negatives using a Nikon scanner. After experimenting with various workflows, I ended up scanning to Nikon NEF, then converting to DNG in batch via DNG converter, then importing into LR. I chose to go that way largely because of it was the easiest way to efficiently add metadata, and because I could convert to compressed DNGs. A lot of scans take up a LOT of storage. I did experiment with adjustments, including sharpening. I noticed no difference between importing TIFF format scans, Nikon NEF format scans, or converted DNG scans.
Sandy