Pooh, many things changed before my transition anyway, so let me first sum that up.
I was quite out before even long before considering transition, and had already subconsciously "specialized" on social contacts where a third or a quarter of my friends were either genderqueer or transgendered (in the sense of feeling like the opposite sex but not planning a transition right now), plus several MTF acquaintances I met regularly for a chat (life - cafeteria or pub). I did not know any transitioning FTMs then and wrongly thought that their passing might not be great either, so I did not consider transitioning. The MTFs never had books at hand or anything where they could show me the end results of FTM transitions.
Another quarter of my friends were just the people dating them, and the last half of my friends were bi/straight/lesbian/gay people mixed. I had never planned to specialize so much on queers as friends, it just happened by chance and I loved it. It felt just silly in this surrounding not to come out for me, and I did come out without caring about it more than, say, coming out as left-handed. But I did not take my male identity that seriously as I also suffered from dissociative identity disorder and knew that this disorder could mimic GID. Plus I thought about 5% of the population were genderqueer and at least 1% transsexual from what I saw around me... and in my statistics, I even took into account that my friends were not representative. It was not a "gender scene" or whatever, my city is not that big, just friends meeting friends etc. In this way, nothing really changed when years later I said I'm gonna transition. My friends were okay with it, apart from one.
Well, I was not expected to HAVE to act like a girl anyway in those surroundings, so in a certain way, I even transitioned at that time and behaved like any other guy, though I still had long hair and often wore fetish goth clothes - mostly hot black silk dresses with combat boots and mesh tights etc. Often, I got amused comments about me moving like a guy in drag. Gosh, these outfits were sexy as hell, and it turned me on a lot wearing them. It was counter-productive for my passing, but so hot that it made me really horny and I just HAD to dress that way as it was very sexy and it turned me on like hell. Transguy with transvestitic fetishism? Maybe...

Docs say that girls rarely have fetishes and therefore don't investigate much in that direction for transguys, but hey ask me and... well... I think it may be different for transguys. And of course, I never told that to my therapist. It's not his business.
Whenever I had a relationship with someone, even before transition, I did not let myself get stuffed into gender boxes. I kinda refused them right away. I surprised my boyfriends with flowers, and they loved it. Etc. I just showed them straight ahead that this relationship was not going to be "gendered" in any way. They feeled relaxed to have a relationship which was like best friends, but also with ->-bleeped-<-ing and being in love, and not being pressed into gender boxes with specific expectations clinged to them. I mean, even straight cis guys may sometimes get tired of being stuffed into gender boxes with lots of expectations etc. and them have to enact a certain role etc. And many of these guys were plain straight and cis. I just did not want to get pressed into the "you're the female in the relationship" box. I did not mind doing "female" stuff whatever that was, but not just because it was me who did it. And well, lots of straight guys were just as happy as me not to feel forced into stupid roles.
Then I had a relationship with a femme lesbian (who was not in the lesbian scene and did not know it well), and she tried to make a butch lesbian out of me to be the male part... but she found out I was really wired like a guy and not just a butch and she went like - okay, you might really be transsexual though you are also multiple *sigh* I'd have preferred dating a girl, but it's okay with you. But if you ever transition, I'll leave you as I'm not into guys. However, I found out there, it flattered me to be the male part of a relationship and to be at least consiedered as somewhat male... but whatever was related to heterosexual partnership dynamics just did not work for me, I rather date equals - you know, real equals. Not I take this role and so have to do X, you take that role so you have to do Y. So I found out that I need to date people who don't want this dynamic either. But she wanted that, though in a different way, but I could not offer her that over time.
So well, in this respect, transition did nothing for me, as I had this kind of relationships with male gay dynamics before, even or especially with straight guys. And I could have them anytime again. I mean, I know a couple of other relationships where one person dates a genderqueer or transgendered person and well... the dynamics depend on the persons' gender and not their sex.
The biggest effect transition had on me yet was that I could finally pass as the gender I feel I am, .
So transition did not change a lot concerning my private life, other than I cannot run around in female fetish clothes with mesh tights and sexy leather combat boots any more everywhere - ->-bleeped-<-!
But let's come to more important things now. Since T and passing I don't feel like people put me in the wrong box and expect behavior that's just not what I get along with but got used to. And my body seems fairly right to me now, I feel more "at home" in my body. I had dissociative depersonalization before as a syndrome, meaning you don't connect to your body, and it's gotten better over time since the start of the T therapy.
The best thing about transitioning is that it helped me improve with my dissociative disorders a lot and -even more - that my body became who I had been inside all the time so it made me feel more "right".