I don't think I would donate. I don't know whether being trans is genetic or not, part of me thinks that it might be because I know/have heard of a few trans people who have trans children/parents, and while I don't think there is anything wrong with being trans, I would rather not be trans, and wouldn't want to be the cause of anyone else having to deal with the pain and all the rest of the jazz that comes with it. Until someone proves that it's not genetic, and nor is my depression and the rest of my mess, I wouldn't want to risk passing it on. I wouldn't even want a child to be from one of my eggs if that ever became a possibility. My feeling is that my genes should stop here.
But, if I didn't have those reservations I would do it. I'm on the organ donor register for when I die, and I'm planning on giving blood, and probably going on the bone marrow/stem cell register, when I'm old enough. If I can help people and do some good with this body then I will, it's not done me any good, but it might help others out. That's assuming that once I get my gender marker changed I'm no longer classed as a woman who has sex with women, but I can't see how they can actually enforce that rule to be honest. Do they stalk people to make sure they're in a heterosexual partnership or is it just trust that you tell the truth?