for that warm and cozy feeling that documents are being safely stored?
You can store everything in ES if you want, some data sets don't care about durability but ES has replica sets and other durability measures so durability isn't a huge issue.
The main problem I can tell from having used ES is that it has no journal for one, which could pose a problem but it is a straight to disk tech.
So that "warm and cozy" feeling is perfectly applicable to ES.
That's pretty much the length of the topic...not too interesting I know.