To me this is a very interesting proposition. I am married and faithful and I absolutely intend to remain that way.
That having been said:
I have always thought that "Mangina" was quite interesting and that it would be a very intriguing experience. It is a curiosity thing.
Having engaged in heterosexual intercourse in my younger years there was a certain design element that worked, but the rest of the body didn't. As a top there is an element of the best of both worlds in it at least in theory, but in practice who knows.
There have also been two FTM's over the years that were equally interesting. To interest me the body would have to be 100% male with muscle and hair. Add a vaginal opening with the proper nerve structure and it could be very interesting.