In term of storytelling, they become stronger soldiers, as they preserve the Yin Energy from being born males and the ability to full conrol it that is exclusive to females.
Kind of, at some point in the game you get the choice to remain male or become a futa. Since I chose the former I don't know how girly the MC becomes but my bet is that their is little change besides some minor dialogue.
It's actually visually more drastic than some of the other characters. Loses a quarter of the height, loses the hood for long white hair, a general color scheme change from black with red to white with pink, and I don't know about the dialogue as I've never stuck with the guy but she does seem less aggressive (than right before the transformation) while still being dominant.
I just realized that the main image for the game on this thread has the female form of the MC.
