There are many theories why Elegance corals do not survive for long. There is a long thread on RC about it and peoples theories on lighting issues, feeding, etc. It is a little more complicated than what to feed. I would not feel to combfortable with 3 months either, that is hardly succesful.
I would do some research on those threads and talk to the few that have had them survive like Dawn. See exactly how they run their setups, whether they have deep water, shallow, what kinds, etc.
Keep in mind that a healthy elegance can get very large depending on lighting. I don't think I would attempt it unless I really prepared and researched for a long time..