*time to attempt to explain my view without coming off as a bigot*
I wouldn't, but if I could modify my body as I please I might do it to such an extreme that I was genderless.
I feel that the differences between men and women is cultural not biological. The biological differences between men and women have as much as an effect on who you are as the biological differences between different men and women. That's how I see things, as I've meet all types of men and women.
The differences we always quibble about "All women do this...""All men are like this..." are due to cultural differences. Within any culture, there is the male sub-culture and the female sub-culture.
So in my opinion no one should fel as if they "have to" change their body to match their gender, because gender is entirely cultural. Your mind is neither male nor female, you think you are one or the other or something else due to culture.
However! If you want to do it: it's your own body and no one can tell you how to use it. I'll argue the philosohpy, but you have the inherent right to your body. Which is also why I support drugs and your freedom to enter risky situations.
So, to reiterate: I'm not against you doing what you want with your body, but I don't think anyone should feel that they need to do it. Same position with plastic surgery.