My african american wife has been with a fair amount of black men and a few white men. The myth is not true. In fact, when we separated, the afro american man she was with for a year had what she thought to be a micro penis. And before she met him (right after we separated), she dated another white man and she said his penis was a little above average about the same as me but maybe a little bigger than me. We have a really open relationship and she is pretty honest when we talk about past relationships. Don't get me wrong, she has seen some big black cocks but she has seen some big white cocks too.
As far as virgina size, a women virgina adjusts to the size of a mans penis over time. I was recently with another afro american woman that screwed allot of black men and had three kids and I was the first white man she was ever with and she was quite impressed with my penis size. Her virgina was a bit loose due to having three kids But I have never really been with a black women or white that their pussy was drastically different in tightness.