Thanks, Sqad. At first reaction the two main comments I would have are that:
a) a better control group might be transgender people who haven't undergone SRS -- or better still, the unknown number of people who have gender dysphoria but haven't yet been open about it. It seems inevitable that gender identity issues are associated with an increased risk of depression/ suicide, so the question ought to be whether or not post-op transpeople are more at risk than pre-op. Not an easy one to assess, particularly as, realistically, society still isn't entirely accepting of transpeople (witness fender's astonishing tirade, or TTT's various ill-informed musings on the subject), a situation that only serves to add pressure.
b) the study itself concludes not that surgery isn't the answer but that it can't be seen as the complete answer. Again, not surprising, as this is what the NHS report published was saying too.