More client projects connecting to one server

   Woohoo!  I have data now!  Thanks for the tip kimj.  Once again you have pointed me in the right direction.In my implementation, I added one line that registers the downloaded component with Ideablade and now the unknown type issue is resolved. 
In the end, I have data in a grid in the host app, from an EF Model that was dynamically downloaded and dynamically queried, where the host app has no reference to the query builder and knows nothing about the EF model or resultant type that is displayed in the grid.  Cool.
Here's the code.  The one line is highlighted pink.

	[Import]
        public IQueryBuilder QueryBuilder { get; set; }

        private void GetQueryBuilderAsync()
        {
            if (this.IsInDesignMode)
                return;

            //use MEF to get a catalog of the specific report query builder
            var catalog = new DeploymentCatalog(this.SelectedReportType.ReportSpecificXap);
            catalog.DownloadCompleted += this.CatalogDownloadCompleted;
            catalog.DownloadAsync();
        }

        void CatalogDownloadCompleted(object sender, System.ComponentModel.AsyncCompletedEventArgs e)
        {
            var catalog = (DeploymentCatalog)sender;
            IdeaBlade.Core.Composition.CompositionHost.Add(catalog);
            var container = new CompositionContainer(catalog);
            container.ComposeParts(this);
            this.RaisePropertyChanged("ShowFiltersRow");
        }