Hi Francois,
Glad you like it!
Currently, the best way to hook up your data model to Breeze is to generate regular Entity Framework entities from the EDMX and expose the EF ObjectContext (or DbContext if Code First) through the Breeze EFContextProvider (as we do in all the samples).
Exposing DevForce entities directly to Breeze is currently not supported. The key use case for this would be to share the same server-side interception logic between the two clients (because the .NET logic on the model cannot be consumed by the JavaScript client). If this is important to you, please vote up the feature on the Breeze feedback page:
https://breezejs.uservoice.com/forums/173093-breeze-feature-suggestions
Hope this helps and thanks for the feedback.