Here is a coming out as trans letter draft, maybe some of you could have a look at it and tell your opinion : http://emptyclosets.com/forum/coming-out-advice/165521-trans-coming-out-letter-draft-new-post.html Hope this is ok to post, since not all have a constant look at the coming out section . (*hug*)
A coming out letter should definitely have the tone set on the one you posted, leaving a door opened to get more information - links to resources, etc. I see coming out letters a bit like suits : They should fit the body/circumstances inside. I think it's a good one, short and to the point.