I have just upgraded to DNN 4.5.3 and you still can't make a portal. You get the following error at the top of the "Create Portal" page after you click Create Portal using a customized Template:

Error parsing Portal TemplateViolation of UNIQUE KEY constraint 'IX_TabPermission'. Cannot insert duplicate key in object 'dbo.TabPermission'. The statement has been terminated. at System.Data.SqlClient.SqlConnection.OnError(SqlException exception, Boolean breakConnection) at System.Data.SqlClient.SqlInternalConnection.OnError(SqlException exception, Boolean breakConnection) at System.Data.SqlClient.TdsParser.ThrowExceptionAndWarning(TdsParserStateObject stateObj) at System.Data.SqlClient.TdsParser.Run(RunBehavior runBehavior, SqlCommand cmdHandler, SqlDataReader dataStream, BulkCopySimpleResultSet bulkCopyHandler, TdsParserStateObject stateObj) at System.Data.SqlClient.SqlDataReader.ConsumeMetaData() at System.Data.SqlClient.SqlDataReader.get_MetaData() at System.Data.SqlClient.SqlCommand.FinishExecuteReader(SqlDataReader ds, RunBehavior runBehavior, String resetOptionsString) at System.Data.SqlClient.SqlCommand.RunExecuteReaderTds(CommandBehavior cmdBehavior, RunBehavior runBehavior, Boolean returnStream, Boolean async) at System.Data.SqlClient.SqlCommand.RunExecuteReader(CommandBehavior cmdBehavior, RunBehavior runBehavior, Boolean returnStream, String method, DbAsyncResult result) at System.Data.SqlClient.SqlCommand.RunExecuteReader(CommandBehavior cmdBehavior, RunBehavior runBehavior, Boolean returnStream, String method) at System.Data.SqlClient.SqlCommand.ExecuteScalar() at Microsoft.ApplicationBlocks.Data.SqlHelper.ExecuteScalar(SqlConnection connection, CommandType commandType, String commandText, SqlParameter[] commandParameters) at Microsoft.ApplicationBlocks.Data.SqlHelper.ExecuteScalar(String connectionString, CommandType commandType, String commandText, SqlParameter[] commandParameters) at Microsoft.ApplicationBlocks.Data.SqlHelper.ExecuteScalar(String connectionString, String spName, Object[] parameterValues) at DotNetNuke.Data.SqlDataProvider.AddTabPermission(Int32 TabID, Int32 PermissionID, Int32 roleID, Boolean AllowAccess, Int32 UserID) at DotNetNuke.Security.Permissions.TabPermissionController.AddTabPermission(TabPermissionInfo objTabPermission) at DotNetNuke.Entities.Tabs.TabController.AddTab(TabInfo objTab, Boolean AddAllTabsModules) at DotNetNuke.Entities.Portals.PortalController.ParseTab(XmlNode nodeTab, Int32 PortalId, Boolean IsAdminTemplate, PortalTemplateModuleAction mergeTabs, Hashtable& hModules, Hashtable& hTabs, Boolean IsNewPortal) at DotNetNuke.Entities.Portals.PortalController.ParseTabs(XmlNode nodeTabs, Int32 PortalId, Boolean IsAdminTemplate, PortalTemplateModuleAction mergeTabs, Boolean IsNewPortal) at DotNetNuke.Entities.Portals.PortalController.ParseTemplate(Int32 PortalId, String TemplatePath, String TemplateFile, Int32 AdministratorId, PortalTemplateModuleAction mergeTabs, Boolean IsNewPortal) at DotNetNuke.Entities.Portals.PortalController.CreatePortal(String PortalName, String FirstName, String LastName, String Username, String Password, String Email, String Description, String KeyWords, String TemplatePath, String TemplateFile, String HomeDirectory, String PortalAlias, String ServerPath, String ChildPath, Boolean IsChildPortal)