At the moment, a content item must be checked in before you can revert it to a previous revision, using right-click, View > Revisions then click Promote on the revision you want. But if someone checks the item out while you are considering which revision to promote, you get an unfriendly error message. Surely it would make more sense if you could promote old revisions only when you have it checked out yourself?
makes sense to me. As I’ve mentioned elsewhere, simplification of workflow and permissions is an area we’re looking at a lot for usability improvements.