Hi Malcolm,
Yes, I saw DBGhost before and believe I even tried to apply it to our problems.
It is a great toolkit and resolves many of issues, actually it could be used in the described process instead of Red-Gate tools, it's just a matter of choice.

Your tool on its own does not resolve database objects versioning issue. It merely compares two databases and outputs the difference. That's a lot, but not the complete solution though. I want to control database transitions from one state to another rather then allowing some tool, even sophisticated one as yours, to decide what should be done. Especially during production system roll-out. I mentioned it - all such tools do it too late. What is worse - managers are assured that all the deployment will be done smoothly without any problem and nothing needs to be done, no system or data understanding is required and so on. When it comes to the reality all the tools are just tools in someone hands. And those people start open heart surgery without even knowing what the heart is. Why bother, they have a tool which knows better what to do! In the end we have untested deployment and a valuable data in unknown state.

Sorry if it sounded harsh.
My intent is to make all deployments identical. If there is a tool solving my problems I would be only glad to use it instead of spending my time on additional development.