I wasn't very clear there. FM8 works in a different way. It has 256 layers available, but you have to decide yourself which style options you want to use with them. It's far different from the GIMP or Photoshop.
Definitely. After one's past the beginners' stage, a good cartographer won't settle for just FM8 or Dundjinni or CC3. One also needs to use the GIMP or Photoshop, as far as I'm concerned. It's only an either/or question at the start.
Another point about FM8, Dundjinni and CC3: They automatically scale things correctly for you.
But then there are the many things that they don't do that the GIMP and Photoshop will do.