I'm 1000% with Bob here . At some point we'll all have to face reality. I've just returned from a five day workshop with Paul Taylor at Renaissance Press doing copper plate Photogravure. It was one of the best experiences ever and the resulting prints are more beautiful than almost anything I've ever seen. The first two days of the workshop were spent discussing and making digital positives using QTR, Piezography and Mark Nelson's PDN. I'm not going into details here, as this thread will I'm sure be zapped in no time, BUT after recently also making digi-negs for silver printing, I am 100% confident in saying that all gaps have been closed. I can make a silver print from a digi neg that could MAYBE only be differentiated from an enlarger one under a microscope. it would be foolish to deny all the incredible possibilities that this brings, including promoting darkroom printing to digital users and to the many who still shoot but only scan film and would be interested in making wet prints without using an enlarger.
To answer your question: no, there is no difference at this point, in a print made from a good digital negative and conventional one. In the case of photogravure, which I will be doing a lot more of, there simply isn't a choice for film positives so I am simply grateful that digi-world allows me to continue and perfect one of the most (if not THE most) beautiful and satisfying processes.