Well I kinda like the sig and the way it's made.
And so,as you requested it you will have a full feedback provided on your work.
So let's start from the compo.
The thingie with the lines pasting part of the signature in there is really good for a composition if its well applied and so it is here.
Also the render is well blended and the idea that's caused the first time you see this sig is "OH FAKS.RIHANNA's got a clone?"
So the clone like effect is well applied too.About depth,In this kind of signature there is no need to have a blurred bg and a sharpened render.The lighting is good but a light source in the middle of their heads would be much better.I also think that a gradient map(violet,orange)on soft light 36% or normal 20% would make it look better.
Or not?
In my point of view the borders should be white and thinner.Also you should make some powerpoints by using the following way:
Make a new layer and brush with a 35 px brush her hands(the color should be a light yellow if you ask me or a deep purple).
After that make another layer and fill it with black.Put it on color dodge and again brush where you brushed before.After that,go @ deviant art,find some pro space stocks and paste them on lighten where you brushed her hands.
This will make the sig look much better if it's applied in a good way!
Regards,MD