At 3-11 you will not hear the truth about what kids think. And we already know with donor insemination that some kids do want contact with their biological dad, which is why the law was changed. Why would that be any different when your mother has actually grown you inside her womb for 9 months?
I think child psychologists can get a fairly good view of whether a child has suffered trauma and is mentally well adjusted. Wanting contact with donors or surrogates also doesn't necessarily indicate trauma- often it is just curiosity.
Also, many gay couples stay in contact with their surrogate. There is no suggestion that Tom Daley and husband will not do so either.
Anyway. Lots of interesting views on here. I am just cautious about anything that suggests that the only ideal family is the heterosexual 2-parent one. I am for a more diverse definition of what family is, transcending biology and looking more at care and commitment as a marker.