If you can get them to stay and they are at the right distance from the lights with the right flow and so on, then it can be really good to do this. You can get more surface area of the coral that gets higher par. Mainly best for SPS, but you usually don't want LPS at the top of your tank anyways. LPS you can place wherever as long at the mouth/head is facing towards the light, so branching LPS are good when properly arranged while others need to be on a flat surface.