Because of how fast/easy ETL flows are, I prefer to use them for most flows. My problem is that sometimes I hit the following error, "Error joining data. The left input cannot include over 10,000 duplicates. Please switch your inputs, group your data, or remove duplicates before joining". The Dojo suggests that this error is only shown to stop users from accidentely making cartesian joins, but I know that's not what I'm doing. For example, if I want to join an item table onto a transaction table, then I have to do it in SQL because I'll get the error. This leads me to having multiple flows for the same end result.
I suggest you give admins the option to disable the error.