It's a really, really gray area for me. On one hand, I'd be fine with it. While I've had sex strictly with women, and I love how a vagina feels, I've been sexually aroused by transsexuals before. Even with that though, I still don't know if I could go through with actually having sex with a transgender, let alone a committed relationship. I'm not the type of guy who likes to do one night stands, and I have issues with dating a transgender on the basis that one day I want to have kids of my own blood; lineage and all that crap.
Also, I'm not a fan of anal sex, and I'd have trouble with sucking a cock. When I've seen transsexual porn a couple of times, I've always watched a "shemale" fucking a woman, or sucking a dick. The ones of shemales fucking men just turns me off. I'd have a hard time both giving and receiving, and if I did manage to get over the turn off of sucking a cock myself, I'd still have issues with anal, especially receiving it.
Thirdly is the voice. I've seen some that have decent voices, but most still sound very masculine, and that would be a turn off to me to be having sex and to be hearing a male voice coming from someone who looks like a female from the waist up.
Fourthly is just insecurities. I don't mean to generalize, but I'm pretty sure most transsexuals are gender confused. They feel like the opposite sex trapped in their current gender's body, and thus have to go to the extremes of surgery to get changed. One of my cousin's is a transsexual and we've talked about this before. Some may be fine with it and aren't insecure, but I'm sure most are. I've dated plenty of insecure women, and that's been bad enough. To be insecure about your gender and your identity is a whole new degree.
All in all, I probably would not date a transsexual. I'd befriend them, not sure if I'd experiment with them or not, but I probably wouldn't date one. That being said though, your damn right I'll defend their rights and fight for them no matter what. They need love as much as anyone else, and not accepting them is only going to make their insecurities even worse.