Some people can't help but just quickly press the "Update to latest version" button when their beatmap is different from the one in the osu! database.
There should be a confirmation that says something like this:
"Are you sure you want to update? Replays that you are keeping on the beatmap will most likely become invalid, or, if you're a mapper, lose all progress you made since you last uploaded this beatmap."
Also, give the option to "archive" previous versions of beatmaps in their computer, so that they won't have to worry about their replays of the top 10 they have in the older versionor if you don't like the new version which made the map all the more crappy. There should be a function that allows you to go to previous versions, either a button or a drop-down list arranged according to the version.
There should be a confirmation that says something like this:
"Are you sure you want to update? Replays that you are keeping on the beatmap will most likely become invalid, or, if you're a mapper, lose all progress you made since you last uploaded this beatmap."
Also, give the option to "archive" previous versions of beatmaps in their computer, so that they won't have to worry about their replays of the top 10 they have in the older version