The other thing to think on is that Brain transplant isn't that essential anyway. If you could create a nano-machine that was capable of creating from the raw materials a whole body. Wouldn't it not be quite a bit easier to set said nano-machine going on the existing body? After all you aren't really changing that much. How the person the change is happening to might think on it would depend on who they were.

If it were happening to me I'd be fairly ecstatic, even as part of an experiment that might lead me to being a puddle of pink goo, hey at least I'd be pink.

There are a huge number of people around the world who for one reason or another want to be able to change their bodies, not just those with gender related issues. But anyone who has a body that is damaged in a fairly major way, paraplegics for instance or amputees.

Nano-machines of the type Xzin is describing could have a massive effect on humanity as a whole, its isn't something we should be going into lightly. The future evil of the sixties was UFOs; in the seventies it was radiation; the eighties was nuclear war; the nineties artificial intelligence; now we should really be thinking about a thimbleful of grey dust that can dissolve someone into their component parts. Or do the same for our whole world...