Another reason to get the extra dress/skillbloom is that they also act as a Hypericum-specific manyu spirit. If you get the extra sealstones from having to run the last map multiple times to 3-medal it for the flower gem, you might as well go ahead and buy them because the currency can't be spent anywhere else. I never ran any calculations, but the XP gained seems to be somewhere in between the lvl 5 and lvl 20 manyus.