I would think that the ability of the colon to reuptake water makes it a better RoA then almost any other part of the body.
I am not saying it doesn't work but the vagina has a different pH and is a less forgiving environment then the butt so if I was a female (I'm not) I would go with normal plugging unless you want to feel uncomfortable, my guess is itchy itchy and burny maybe not forever but I wouldn't want that at all