It's not that I am against it, or would advocate that the first thing you say to a person is 'Hi, my name is Xxx and I'm a transsexual'. But, I'd rather keep it somewhat similar to any other medical conditions. Meaning, you don't advertise them, but you don't really keep it a secret from people who know you or people who has a need to know.
Imagine a cis-woman who won't be able to conceive a child. It would be expected that her future husband knows of this little fact before they both say 'I do'. Would any lady's boyfriend need to know? Some might in a context - don't worry about protection, I trust you and I cannot have a baby. But some may never know.
Would your employer need to know if you survived a cancer? Maybe not, unless you still need some accommodations from him. Yet if you do, you would be best to address those before you accept job offer.
What about religious people who might be offended by your past? I'd say their beliefs are their problem, they had eyes to see and if they couldn't - it's their problem, not yours. Although it would be wise not to invest too much time into a community that would not appreciate you for who you are.
At the end, I know it's very liberating not to have people around you treating you differently from any other person, but is it healthy to trade one 'dark secret' (be it a crossdressing, or desire to be a woman), to another? I think those who openly say 'I want to be a girl' from early on, not hiding their crossdressing from the world (or openly wear androgynous clothing before transition, and not hiding about their transition either - are surrounded by people who ultimately accept them, and as a result they know they can rely on them.
What are your thoughts?