The grain stays the same. The stained image behaves differently with VC and blue sensitive printing materials, which is one of the advantages often quoted for PMK and other staining developers. If you use hydroquinone, it is no more dangerous than most of our print developers. I have not compared the results with selenium, but I don't remember that one can use selenium more than once. Anyway, I suggest a trial on something not important just to see what it can do by comparison with selenium. You probably have on hand everything you need.