Earlier this week, I wrote a post discussing when I would choose querying an data through an Entity Data Model using LINQ to Entities vs. Object services + Entity SQL vs. EntityClient + Entity SQL.

One of the advantages I pointed out about using EntityClient is that it returns datareaders and does not attempt to turn the returned data into objects. In re-reading Zlatko Michailov's EntityClient post from earlier this year, I realize that I didn't highlight one of the most important reasons about being able to return datareaders, in case it isn't obvious: Performance. But note that this is for reading only.

If you do not need the Entity objects materialized by object services and do not need the other benefits of object services (e.g. change tracking and DML) and just want to get your hands on the data, using Entity Client will get it to you the most quickly. While this can also be done with ADO.NET, EntityCLient gives you the benefit of querying the conceptual model rather than directly against the database schema.