using stored procedure function mapping for updating data

In my model I'm mapping the update function to a stored procedure.

I assumed updating data via DevForce EntityManager would result in the same update statements as updating the data directly with EF. But it's not.
Have a look at this code and the generated update statements as comments:

            //use EF to update data
            using (var ctx = new Model.testEntities())
            {
                var t1 = ctx.Tests.First();
                t1.Value1 = "new value x";
                ctx.SaveChanges();  // -->   exec [dbo].[procTestUpdate] @ID=1,@value1='new value x',@value2='value2',@valueInt=1,@valueDate='2010-01-01 00:00:00'
            }
            
            //use DevForce to update data
            var manager = DomainModel.DomainModelEntityManager.DefaultManager;           
            var t2 = manager.Tests.First();
            t2.Value1 = "new value y";
            manager.SaveChanges();  // --> exec [dbo].[procTestUpdate] @ID=1,@value1='new value y',@value2=NULL,@valueInt=0,@valueDate='0001-01-01 00:00:00'

In EF all values are passed to the stored procedure, regardless whether their value changed or not. Using DevForce only the values of the changed properties are passed and the others are null or default.

Is it posible to change this behavior? Is there any documentation and best practice about writing update procedures in "devforce style"?

DevForce 2010 now support entities backed by stored procedures, as of version 6.0.3.