The built in tools for Entity Framework 4 in Visual Studio forces users to make a distinct choice between the “Database First”, “Model First”, or “Code First” model creation and update strategies. A recent MSDN Magazine article by Julie Lerman describes the options and choices that has to be made on which approach to use for updating the model.
I think those three choices are a bit limiting in that not being able to continually evolve both the model and the underlying database is not an ideal situation for many projects. Applications evolve and so do the underlying databases, often with changes made by several people using different tools. That is the reason why I created the Model Comparer for EF4 in the first place.
Even if the model is based on an existing database, a.k.a. ‘Database First’, I think it should be possible to use the EF designer built into Visual Studio to update the model and add/remove/change entities/tables, members/columns, associations/foreign keys etc.
Likewise, if the model is designed from scratch in the EF designer (‘Model First’), it should be possible to make incremental changes with SQL-DDL diff scripts, as well as making schema changes directly in the database and sync those changes back to the model.
I made a short (4½ minute long) screencast illustrating how this is possible to do with the EFv4 visual designer together with the model comparer. In this video I make changes both to the database in SQL Server Management Studio and to the model in Visual Studio and then sync it up to replicate the changes into both the database and the model.
The video above is also available on youtube at http://www.youtube.com/watch?v=doqYOlcEAZM , although the youtube version is lower resolution and has more MPEG compression artifacts than the one embedded above.
Oh, and if you want to try it out yourself, you can download the add-in that makes this possible from http://huagati.com/dbmltools/ and get a free trial license from the same site.