Mixed race men that I know seem to have more luck than mixed race girls in my experience in finding relationships. I think this is because white women are generally more willing to date black/mixed men. They also don't have a preconceived notion of them and tend to accept them as they are, a quality I don't think most white men have towards black/mixed women.
I can see various pros and cons that mixed women may find when dating white men and black men and the mixed men available to them are far and far between. Even if they were to meet one that doesn't mean that mixed man would magically be good for them.
1) they can at times exoticize mixed women
2) the mixed woman they are dating may either not be white or black enough for them. Most black men I know prefer to date white women, so a mixed women is just a kind of stepping stone for them.
Those that like black women tend to date black women who have fully grown up in a black rather than mixed culture; a true black women who can cook soul food e.t.c.
There are some black men who accept mixed women as they are but these tend to be alternative type black guys who have probably not grown up having a strong black identity themselves. eg. the character in the film 'I'm through with white girls:
3) their insecurities when dating mixed women. Wale has addressed this in his song 'shades':
I myself have dated a black man who let his insecurities show and he did mention my mixedness so I wonder whether he felt that I would not take him seriously because he was darker than me (insecurity is not attractive).
-On a positive note black men do tend to see mixed women as beautiful, at times it can be seen as exoticizing. But not always. The singer keke wyatt has mentioned that she feels that she is more so a black man's standard of beauty than a white man's, which is why she has tended to date them. Black men also tend to appreciate curves on women more. They also do not shy away from speaking their mind and talking about race or other passionate topics, which I think is a good thing.