Seen these discussions?
https://news.ycombinator.com/item?id=23285249
and
https://news.ycombinator.com/item?id=23290844
Turns out Mongo still has major issues with data consistency.
And unfortunately Meteor still only officially supports Mongo.
It would be awesome if Meteor would officially support Postgres. Hosting Mongo is a hassle these days (basically only Atlas), it’s expensive, and as can be read in these discussions, not very reliable.
(Disclaimer: personally never had a problem with Mongo but the problems seem real at bigger scale)