Oddly enough, it was the Night Vale fanfic community that helped me to understand some of the issues that trans people are facing, and to better empathize with them (even so much as trying to figure out whether they can go to the bathroom without making anyone else uncomfortable or getting harassed themselves). I'm quite grateful for that, as I'm writing a couple intersex characters in the cast of an upcoming project, and while they aren't major characters I did want to treat them as human beings and with appropriate sympathetic awareness of what their reality is like. I just didn't expect to find that via fanfics of a guy dating a thoroughly endearing tentacle beast (life is funny sometimes).
I don't think I could ever be comfortable marrying a man who is genetically female -- but that's tied in with my religious beliefs, that the soul at its creation (first breath) has a gender, that the genders have particular characteristics to highlight deeper truths about reality beyond our limited space-time, that a corruption or "curse" happened across all creation when Adam sinned and that it blurred the lines between genders (essentially, we had a Platonic ideal two-party system beforehand, and that got all screwed up). But I equally wouldn't marry a man with long hair or earrings, and for roughly the same reason (symbolism of deeper truths), so it's not like gender is The One Big Thing with me; it's just a set of standards that I've grown up with.
(And I do think that gender identity is tied to getting the wrong hormones in the womb (they've done this with rats, and they'll totally act like the opposite gender), so it's not the person's fault that they feel this way, and since it's the brain doing it and not a choice, it makes zero sense to harass them over it. How they care to dress or talk or whatever is nobody's business but their own, and it's not like it's hurting anybody.)
I think I could marry an intersex man. I don't believe that God meant for the entire group of intersex people to be celibate, nor indeed to marry only other intersex people, so it makes sense that they should be acceptable in normal marriages and I shouldn't have a problem with it. Intellectually, I think it shouldn't be any weirder than marrying a guy with any other genetic abnormality or deformity... though I don't know how I'd feel about it if I actually were in that situation, and sometimes our feelings don't match our rational understanding of things (you can be disgusted by something that you reasonably shouldn't find disgusting). And in my understanding, intersex covers not only visibly weird stuff between the legs, but also just having a genetic setup that doesn't clearly indicate either male or female (XXY, XXXY, etc.).
I haven't read this entire thread yet but it cheers me to know that the transgender community also thinks it's wrong to deceive someone about your full gender profile en route to sex/marriage. I know that if I ended up married to a guy and found out he'd been born female, I would flat-out divorce him -- not over the gender thing in and of itself, but because failing to share that at an earlier stage in the courtship says some incredibly dark things about that person's character and especially their respect for me and my right to informed consent ("she'll never find out so she doesn't need to know" is like the opposite of respecting me as a person). (Rape by Deceit is an issue I'll be tackling in my project. Like a decade ago I saw an Oprah special about men who realize they're gay after marriage, don't tell their wives, and start sleeping around... and at the time I saw it, I got vibrating mad and saw it as way worse than mere cheating, and I didn't even know why I thought that. Turns out that the statistics back up my intuition: Men who sleep with men are an ASTOUNDINGLY huge jump in STI risk compared to a guy who cheats with other women.)
But, on the other hand, Leftover Soup made me think it over: Where along the courtship line do you say stuff like this? "John, I'm not sure how far this relationship is going to go, but I thought you should know something about me. Or rather, about my body...." You need to convey this information clearly prior to any sexual relationship of any kind -- that includes kissing! -- and prior to getting engaged. But just how far back do you go? And how much do you have to trust a person before you share with them some intimate part of yourself, a secret that could get you fired (still happens!) or ruin some of your relationships to friends and family? And that's not even taking into account the amount of social and linguistic dancing we do to avoid stating the facts in a clear and straightforward manner, or the fear of seeing a relationship crumble after you were taking such comfort in it up to that point. It's a complex issue.
