Who to replace

I have a Rappa e0s1, fugue e0s0, RM e1s0, and Gallagher e6 with his sig LC. I also have a Boothville e0s0 that I sometimes use based on the content. Based on what I read, Dahlia is tailor made for FF so I am confused on what stats do I need on Dahlia to suit Rappa. Is she a significant upgrade over RM or fugue?