With dogs in general, it's usually recommended that you go with opposite sex pairings. Maybe it's not as big of a deal with yorkies as it is with bigger dogs, but generally the boy falls in love with the girl and just lets her walk all over him.
Sometimes you can get female-female squabbles, and male-male fights. Opposite pairs are safest, but that doesn't mean other pairings can't work. Depends on the owner and the dog. I have to say though, that male is gorgeous! Go for it!