Regarding the dutch study
I suspect that as more and more gay relationships get confirmed through marriage, and more young gay people see positive, affirming examples of committed same-sex relationships, there will be less and less focus on promiscuity among young gay people, any more than there is a focus on young heterosexual people.
This topic took a turn to ex-gays and I suspect (and I think this is backed up by at least several studies?) that homosexuality is not a binary, quantum identifier but exists along a spectrum from -- say -- 90% homosexual to 10% homosexual. So perhaps the ex-gays really are ex-gay, but were never THAT gay to begin with? Just a thought.