It would be extremely helpful to be able to the differences between the two sites. We try to pull the live site down to staging whenever we start a new project so that we can push staging up to live when we are done without worrying about overwriting anything on live. We have a lot of clients, so keeping up with whether or not we have projects sitting on the staging site and trying to figure out if the client has made any changes on the live site proves difficult. Being able to see the differences between the two sites before merging would be extremely helpful; even if it's just the sql tables.