It takes no more effort to open a RAW file and edit it and save it as in the open TIFF format than it does to save it to the proprietary PSD format. ... At least I was never suckered into the Adobe DNG format which provides no advantages at all.
DNG does have one advantage, IMHO, and that is one can edit a 'raw' image with a tool such as Lightoom and not have to worry about an XML sidecar file to store the edits. Drives me crazy to have two files for each image to worry about. Converting my raw NEFs to DNG when importing removes that necessity, as Lightroom's adjustments can be stored as metadata in the DNG file itself (as well as the LR database, of course) instead in a sidecar.