I certainly see Cyclops as older too, but I think what people are forgetting here is that it's kept vague for a reason. Unless there's a real story need (and that's a rare thing), there's no reason to pin it down. It's like you say, internal continuities. The worst thing that people can do is try to force a situation where there's reason to pin it down, because when it comes to character decisions, ultimately, you've got all the cards. There's plenty of room for people to see him both ways.