Regarding my early name change: I first realized that FTMs existed when I read a book about the subject--apparently the first clinical book ever written about FTMs. The author essentially said that we are all women who need intensive therapy. Thinking I was mentally ill, I labeled myself a cross dresser instead of a transsexual. That went on for about five years until I discovered the term "transgender." Now convinced that Dr. Lothstein was a raving dingbat, I immediately adopted the new label "transgender" and started doing more research about hormones and surgery. But I felt that I couldn't transition medically because of various roadblocks.
I already presented as male and was sometimes read as male--but less and less often as time went by. And without a plan for hormones and surgery, I was going nuts. After a couple of years of this, I realized that I needed to change my name. I think the change saved my sanity in a way.
The cons? Yes, some people did get confused, but most of them thought that my first name was my last name. Some of them thought they had misheard me, so they wrote down or uttered a female name that sounds sortakinda like my male name. I ran into a few people who thought I was using a husband's credit card, a few folks who asked for ID when I wasn't expecting them to, and a few folks who commented about my unusual name. These situations were a bit awkward but not really a problem.
I was accused of identity theft once, however. I imagine that such accusations would be more common now, since people are much more aware of ID theft than they were back then. I finally convinced the guy that I really was who I said I was.
One advantage to changing my name well before transition was that it established me with that name. One disadvantage is that it linked the new name with the female sex and the female pronouns. So I still have a number of student reviews on Rate My Professors that use the female pronoun. That's maddening, and I feel that the reviews out me.
If you ever need references or a recommendation from a former boss who knew you with the old name before transition, that could be a problem.
I retroactively went back to my former schools and changed my sex in their databases years after I had left. This was just something I had to do.
The biggest advantage was emotional. Even when I regressed deep into the closet again, my male name was a point of pride, a big f*** you to the world, and a not-so-tacit reminder for myself of who I really was. I guess my name became a major coping mechanism when all hope seemed lost. Looking back, I think I needed to do it to survive.