Hi Line,
"Give Portal users the possibility to create new Feature Layers from Portal. From what we understand this can only be achieved if we use ArcGIS Data Store; using an Enterprise geodatabase as our Data store does not unlock this options."
This is not correct. This works fine also with SDE Enterprise geodatabase, like in Oracle. You may also use the same geodatabase as you are using for other purposes (I do not know if this is recommended, and may of course have impact on response times). We do, and have Portal create new feature classes in a separate Oracle schema.
One benefit of using Enterprise geodatabase, is that the feature classes that users has created is visible as you are used to, like in Catalog. You may also read the feature classes from the Enterprise geodatabase with other tools.
(You might actually also overwrite data in a feature class created from Portal, with ie a FME job, if you have permission to the Oracle schema. We do this to help users get their data updated regulary.)
A constraint is that column names are limited by Oracle column limitations, and when users do like Share from ArcMap to create a new feature layer in Portal, this will fail with a 99999 error message with no further information, if their data definitions are rejected by Oracle. Column names that are accepted in a file geodatabase may be rejected. The most common issue I have encountered is column names longer that 30. Hopefully this works better with Data Store, it should accept all data types that accepted in a filegeodatabase. I have no experience with this.
Regards,
Lars