Well, I am not the “asshole” in question, but I can tell you what my textbook (Abnormal Psychology, 13th ed, Butcher 2006) says, because I just read the section on GID.
“Psychotherapy is usually not effective in helping adolescents or adults resolve their gender dysphoria (Cohen-Kettenis, Dillen, et al., 2000; Zucker & Bradley, 1995). The only treatment that has been shown to be effective is surgical sex reassignment.”
“A 1990 review of the outcome literature found that 87 percent of 220 male-to-female transsexuals had satisfactory outcomes (meaning that they did not regret their decisions) and that 97 percent of 130 female-to-male transsexuals had successful outcomes (Green & Fleming, 1990). More recent studies have reported similar findings. Thus the majority of transsexuals are satisfied with the outcome of sex reassignment surgery, although there is variability in the degree of satisfaction (Cohen-Kettenis & Gooren, 1999; LeVay & Valente, 2006). In spite of the reasonably good success record for transsexual patients who are carefully chosen, such surgery remains controversial because some professionals continue to maintain that it is inappropriate to treat psychological disorders through drastic anatomical changes.”
Does that count?