Just remember they require feeding daily and have no capacity to photosynthesise which means if you don't keep up the feeding it will die quite quickly.
Black or orange... Have you made the commitment to nightly feedings, increased maintenance and teetering on he brink of Eutrophia? I have 6 now (3 black, 2 orange, 1 pink and yellow). It's hard, hard work. But I love them!
Orange are easier and less susceptible to polyp bleaching.