I see questions about changes/lost options since Opera 7.5 all the time, and people are kind enough to answer these questions. However, I think it would be a good thing to simply point people to an article in our knowldge base, explaining how to migrate from Opera 7.5 to Opera 8. That way, people can get a list of most of these things, and they can spread the URL to other people.
You know the saying: "Give a man a fish and you feed him for a day. Teach a man to fish and you feed him for a lifetime."
Encouraging people to search for existing information is always a good thing, as it saves everyone's time.