I use rubber and metal currys depending on the extent of the dirtiness. I prefer rubber but if the horse has dried mud caked on their legs and belly, I'll gently use a metal curry to get the majority of it off, then switch to the rubber curry for the remainder.
Yes. My answer is yes.
I use whichever curry type device I happen to get my paws on first. Sometimes it is the grooma, sometimes it is a cheap-o plastic model, sometimes it is the rubber type with the little teeth on the edge.