Elegance corals need to be mounted vertically instead of horizontally as this is their natural position on the reef. Evidently they will not survive otherwise...this could explain things a bit.
As far as deep water corals go, elegance corals have become harder and harder to take care of. In the early years of reefing, elegance corals used to be very hardy, but now they have become fairly difficult to keep. People used to be collecting elegance corals from the sandy costal waters in very shallow areas. These were much more hardy, and have a brighter green color, with fatter, and wider tentacles. These corals also depended more on their zooxanthellae to receive nutrition. The difficult-to-keep elegance corals are usually collected from deeper waters, which tend to have a paler color to them, with usually longer tentacles.
Most elegance corals sold on the market are the deeper-water species, and will need a nutrient rich environment. I would stay away from buying them, as they can be difficult to keep.
Graham