Now hang *on!* You can't separate power from gender, a point which I recall has been made by Neil, Una, Alison and myself among *many* others on this list.
Try this: Servalan has a submissive man at her feet. She steps on him and continues walking on. Or she talks to him only to find out how useful he will be. She tells him she will help him after she recovers her pilot. They rescue the pilot. She shoots the submissive male and goes on her way. Cally has a submissive man at her feet. She gets him to stand up, asks many questions showing a keen interest in what he thinks he is doing and why. She helps him with his request, then asks him to man the door while she rescues the pilot.
Same gender-reversal in both cases. Servalan is evil because she's evil, not because she's a woman. Cally, in this scenario, does what Avon did-- because they are neither one the sort to abuse power over another person.