... may not be right for anyone else. I have to say that I am having some pretty major difficulties wondering if I want my condition (transsexualism) to be considered a psychopathological condition or not. Yes, there is mind-body incogruence. But other than that and a nagging shoulder issue, there isn't anything really wrong with me. I'm relatively happy, having enough positive things happening in my life to balance the tendency toward depression directly related to a surgically treatable physical defect (having a male body). Sociologically, I think labeling something as normal or abnormal is not just a scientific definition of norms and being outside of them, but society automatically assigns good (norm) and bad (not norm) values to things defined that way.
On the other hand, in this economic and societal climate, I cannot envision insurance companies (the few that currently do anyway) covering gender reassignment surgery if gender identity disorder was not classified as a psychiatric pathology. So is having that covered for some people (not me, mostly folks working for a few open-minded large corporations) worth being labeled as a nutjob? Actually, even beyond the economics of it, having an official medical diagnosis can be helpful when coming out as well. "I have GID, look it up," is much easier and more convincing than "I believe I'm a girl, I want you to respect that and treat me as one from now on, ok?"
Of course, as others have already noted, categorizing transsexuality as a physical genetic defect - perhaps something like "X-Y chromosomal substitution" - might be the best solution. It doesn't imply any impairment of my ability to think, but medically treatable and such treatment affords substantial improvement in quality of life. Insurance companies regularly cover a variety of birth defects with that kind of description.