Well when Desmond turned the key, the sky went all violet but when the island was moved by Ben, it went all white.
So not sure if that means anything. Also I'm not sure how turning the key would move the island. How would Dharma be able to rig a key to make the island move? If there was an easier way to move the island then turning the wheel wouldn't Ben have done that? Especially if it would allow him to stay on the island after moving it, like Desmond was able to. Also, Ben and the Others seem to know a hell of a lot about the Dharma stations and experiments so if the Swan had an easy way to move the island why wouldn't they take it over so they could use it if needed?
This also brings up the Button issue. I don't think pressing the button "saved the world" or anything like that. It might have stopped a major explosion of something, but nothing super dangerous. Otherwise, the Other's would have taken the station over themselves. They definitely had the man power to safely keep pressing the button, rather then leaving it in the hands a lone man who may or may not kill himself or hurt himself or run off and not press it. I mean the Others want to keep the island safe, so if the button actually did anything major, they would have been pushing it to keep the island safe not let someone else do it.