Informed consent is a tricky one: if the less-intelligent participant is enthusiastically participating in, even initiating, sex with an uplifted person of very similar morphology and sexual signals, I have trouble coming up with reasoning under which that isn't informed consent in which an animal of that species can consent to sex with another non-sapient member of its own species.
There might be a profound "ick" factor, either stopping the uplifted people from consenting to sex with non-uplifted members of their own genus, or causing them to be scorned or worse by other people: "what kind of a weirdo is he, he has sex with the ones who can't talk?" "Can't zie get a real partner, someone who knows zir family?" "The only people who have sex with wild wolves are so inept that no actual person would even give them the time of day" "It's wrong to sleep with the soul-less, throw her in jail before she corrupts the young!"
And, of course, the possible creation of half-sapient offspring would probably affect opinions.
(no subject)
There might be a profound "ick" factor, either stopping the uplifted people from consenting to sex with non-uplifted members of their own genus, or causing them to be scorned or worse by other people: "what kind of a weirdo is he, he has sex with the ones who can't talk?" "Can't zie get a real partner, someone who knows zir family?" "The only people who have sex with wild wolves are so inept that no actual person would even give them the time of day" "It's wrong to sleep with the soul-less, throw her in jail before she corrupts the young!"
And, of course, the possible creation of half-sapient offspring would probably affect opinions.