When using the new import feature you can only import a dataflow model that has the AllowNativeQueries attribute as FALSE. There should be the capability to either:
import dataflow model JSONS where this attribute is TRUE
modify dataflow JSON and republish without having to go through the standard edit screen which can take FOREVER for it to load a preview of data and validate the model.
My big beef with dataflows is that often times I'm making a small modification to the SQL associated with one entity (i.e. adjustment to the WHERE clause that has no impact on columns returned). With big entities it can take forever to make these updates as 7 out of 8 times the query validation will timeout after 10 min.
I know this is less business ETL oriented but I'd love to be able to modify the JSON, i.e. SQL query and columns, etc. without going through the slow validation process. I was hoping to be able to export JSON models, make minor adjustments and then import as a new dataflow but AllowNativeQueries has to be set to false on import meaning that in order to get the dataflow to run I would always have to do the UI edit/validation process which again takes forever.