This is great, but it doesn' appear to work AS well for Entity Framework when you are using inherited types (Table Per Type).  I am able to retrieve full data (including the entire derived data fields) based on the common object id (I use a Guid).  But unlike accessing the data directly (where I can specify a where clause on some of the derived class properties) it seems that I cannot achieve this when accessing the data through the service.  So for example, if my derived type has a field 'Name' then I can't query with [from c in entities.DbObject where Name == "Mike"].  Doing this directly requires (AFAIK) the use of the OfType<T> extension on the root object (in this case, 'DbObject' is the base type) but the Data Service clearly tells me that I can't use it.

Is this accurate, or is there something that I'm missing?

-mdb