I really believe the biggest benefit is the ability to check and validate objects on the fly. This will point out errors with the changes as you make them; this is nice. As far as the build in schema compare and data compare Red Gate does a FAR better job at this. Of course you have to pay for those tools but the added cost is worth it. DBPro does not allow you, from what I can see, the ability to set up a reusable definition of your comparison projects something that Red Gate does nicely.