Maintaining a data layer is a big job. If you plan to implement it and maintain it go for it, but the project will keep on changing and it will constantly need updates to keep it working. I think its a very corner case using SQL CE, a lot of work and very few people would use it.
There is some linq to db stuff in the Mono project that might work with SQLite. VistaDB support would be more desireable than SQL CE. Unlike SQLite, VistaDB can work in medium trust hosting (or so I've read). In any case its a lot of work supporting additional databases. I have no immediate plans to support additional ones myself.