There's a great review that Lawrence Wilkes has published on our designers on the CBDI Forum that's definitely worth a look:
Reponses to some of the issues Lawrence raised about our designers:
1. White boarding limitation: You cannot easily add ExternalWebServices, BizTalkWebServcies or ExternalDatabases to the diagram unless they already exist.
We have made some changes in this area in beta 2. Adding an external database no longer requires you identify a database up front (although even in beta 1 you could cancel out of the dialog and still create the External Database). The dialog to define the database connection is popped up when you connect to a database, but can be dismissed without canceling the connection. The connection information can then be added later. We don’t yet have the same flexibility with external web services, although this can be mimicked by creating and referring to a temporary WSDL file initially. When the contract is known you can then reference the correct WSDL from the external Web service and refresh it, which will refresh the proxies of all connected implemented applications. As white-boarding is one of our key scenarios your input is valuable - we may revisit this after beta 2.
2. Whilst you can add a new Web service, currently there doesn’t seem to be a way to change this to an External Web service.
While the project that defines the web service is within the solution it will be considered to be ‘internal’. If after implementation you remove the Web project from the solution but retain references to it in other applications then it will be replacedon the diagram by an External Web Service..
3. What if the external web service provider wants to change their Service definition as they work towards completing their implementation?
If the WSDL definition associated with an External Web service is updated to reflect the change, refreshing the External Web Service will update it and the proxies of all connected implanted applications.