Hello Brian Pratt,
You have posed quite an intriguing question. Providing an automated way to save all your data in a file, work with it offline and later synchronize the changes to the database goes slightly beyond the functionality of an ORM tool. OpenAccess ORM is optimized for working with the database on the fly and offers a transparent way to handle connections efficiently. You can load objects in memory, perform some operations with them and later save the changes to the database by interacting with our special context and scope objects designed to encapsulate the database connection and transaction handling.
Working with SQL CE is an alternative as you have mentioned. Since you cannot find a common data type base for the models of your existing and new databases, you can work with two conceptual models. However, the synchronization logic should be written manually. You can use two context objects and perform some merging operations while having the the two contexts active. Yet, this is not done automatically as an ORM tool concentrates on working with one database at a time. You can change the connections and connect to different backends but at one moment you interact with one database.
Do not hesitate to contact us to further discuss scenario you have described.
the Telerik team