The problem with reflection maps or scenes, they don't always match the background stage.  If you are only interested in creating an image as above, then a map would be enough.  But look closely, the reflections do not match what the character is wearing.  However, if your image will be placed in a populated scene, you would like to have your chrome actually reflect what is present.  Outdoor scenes will require a skydome, indoor scenes should have a completely enclosed set.