agree with comment. We use ES quite extensively as a database with huge documents and touchwood we haven't had any data loss. We take hourly backups and it is simple to restore. You have to get used to eventual consistency. If you want to read after writing even by id, you have to wait for the indexing to be complete (around 1 second). You have to design the documents in such a way that you shouldn't need to join the data with anything else. So make sure you have all the data you need for the document inside it. In an SQL db you would normalize the data and then join. Here assume you have only one table and put all the data inside the doc. But as we evolved and added more and more fields into the document, the document sizes have grown a lot (Megabytes) and hitting limits like (max searchable fields :1000 can be increased but not recommended) search buffer limits 100MB).

My take is that ES is good for exploration and faster development but should switch to SQL as soon the product is successful if you're using it as the main db.