I'm always the black sheep when it comes to background colors. Some fish (red/gold severums, psittacus, etc.) look awesome on a black background, but some fish tend to try and blend in with their background and they end up always looking dark or washed out. Being a discus keeper first, I tend to always go light colored because dark colors will cause discus to go dark. I have noticed that my notatus severums show heavy bars in dark tanks but they tend to show no bars in a light tank.
When it comes to orangeheads, they do look great in a tank with a dark background. You may want to use light sand, though. I think dark sand and a dark background is just too much. It's all personal preference really.