Thanks for your comments.  I guess it all boils down to what pushinfaders wrote: "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."
That leaves a bit of freedom for interpretation.

My problem is more personal as I feel that manips don't fit in my gallery. I can't mix manips with "normal" photographs. Feels a bit like being schizophrenic (which I'm not, and neither am I).
I'll have to think this over.

As for panorama shots from multiple captures: I forgot to mention those. Theoretically they are manips, but practically they are like composites (hdr) to enhance or extend the luminosity range.

There are no Borg. All resistance is fertile.