The purple one is interesting. The effect is different, but interesting in how it will differ so much from the other shots, plus just what her costume's details are. They blend in a way that adds more.
I wonder what it would look like, if both danced together in those costumes. I suspect it'd be
evocative of the old Disney Fantasia film's certain sequences. Yet, not animated in that style. Even a kaleidoscope like effect perhaps?
it's hard to tell if the change is just b/c of costume b/c I have to make constant changes to the shutter speed and flash as I shoot based on how far away they are vs. me and how fast they move and if the light changes at all in the room. Some could be the costuming... I'm sure that orange blends more interesting with the background, but some could be my fault for the way I set stuff up.
The other benefit when they are in a big room like that where the flash might not light up the whole room is you won't end up with a person illuminated and a black background where it looks like they are standing in a cave.