My gay friend couple only engages sex with each other exclusively, and both of they are healthy. So I don't think they even need a condom for sex as it is safe. If I tell them that, it wouldn't offend them any more than it offend a straight couple, if at all. AIDS is simply not a health concern for them whatsoever. It has nothing to do with them being gay or not, but how responsible their sexual behaviour is.
So In a developed country like Canada (to exclude cases due to poor health conditions and poorly managed blood supply), I believe the probability of catching AIDS has little to do with homosexuality or heterosexuality. I mean theoretically if a gay person only has sex with his partner (who is also exclusive), he is very unlikely to get AIDS; On the other hand, AIDS has a lot to do with how responsible one's sexually behavior is. If one habitually engages sex with multiple random people, then he/she is a lot more likely to catch AIDS, let him be straight or gay.
I am not an expert, but I think this is how AIDS works, right? Correct me if I am wrong.