Here is something I do quite often:
1. open a PDF file at resolution 600dpi
2. paste a scanned signature onto it
3. add some text to it
4. scale the image back down to 100dpi
5. save it as a PDF

Photoshop handles a number of these steps better than GIMP.

In #3, I have to use something like a 90pt font size, so that it will
be correct when I scale it back to 100dpi.  Photoshop just "does the
right thing" when using, say, a 12pt font on a 600dpi image.

In #4, I have to both change the resolution *and* change the
dimensions of the image "by hand".  Photoshop again "does the right
thing" and adjusts the dimensions according to the new resolution.

In #5, I have to create PDF output awkwardly by using "print to file".
Photoshop just lets me "Save As" PDF.

Thanks for considering/forwarding these wishlist items, and for
maintaining GIMP in Debian.