We have recently used Survey123 with submitted surveys and form template published to our federated Portal account. This feature layer, however, is "Hosted" in the Data Store and cannot be related/data linked to our other feature services stored via ArcGIS Server through our enterprise SQL/SDE system. This makes the Hosted data very difficult to use in applications since the schema and storage is so different, other than yanking a copy each day to our SQL so the various layers and "communicate". While I realize Survey123, Portal and the hosted Data Store are all relatively new applications and organization, it would be GREATLY appreciated if ESRI moved forward with correcting this disconnect.
One very helpful option would be to simply publish our data directly to our SQL/SDE database to begin with from Survey123 and exposed as a regular service rather than in the "Hosted" Data Store. Rather like Collector behaves (editable feature service from our own SQL/SDE).