I had a purple psuedo, which is about the same as the bicolor but with all purple. He ate a full grown peppermint shrimp whole! The shrimp was about the same size as the fish. They did live together for a few months before that though. I would definitely get the shrimp first if you decide to get both.
Also, the psuedo is likely to be surprisingly mean. IMO, they are meaner than damsels (or at least equally as mean). The royal gramma is supposed to be much nicer. Although I've never owned one.