Correct me if I'm misunderstanding. But it sounds like you're saying that the "gender" option should read as follows..
Male
Male (*insert proper term for one who has had gender re-assignment surgery, which I do not know*)
Female
Female (*insert proper term for one who has had gender re-assignment surgery, which I do not know*)
If that is the case, then, keeping in mind that I know nothing of the desires of other people, don't think this would be wanted. It is my (admittedly limited) understanding that someone who has gone through such trouble to change their gender, will want to be identified as their gender. Ex, a male who was once a female does not want to be thought of as "A male who was once a female". He wants to be thought of as a male.
Again though, this is a potentially touchy subject, and I don't really know much about it.