"heavily manipulated images should be uploaded in the "photo manipulation" genre.

Images that contaiin non-photgraphic elements (such as fractals or 3D elements) belong in the Mixed medium gallery"

To me that is clear enough.  It is up to me to determine how manipulated is the image. I convert to bw in software, I sharpen in software...and do a few other things.   With digital, to shoot in bw is not wise and sometimes the camera will not do it. To sharpen in camera can lead to halo problems...and other things.   So, just as my dad did many, many years ago with the basement darkroom, dodging and burning, perhaps cuting out an "unsharp mask" and tricking the baths, I do in software.  That is not manipulation..that is the art of photography and includes much I did not mention.

So, I will simply decide if "heavily manipulated" or not...and if mixed media then there it will go.  Each contributor here has that choice to make.
Sounds ok to this Tom.