I also have similar skepticism towards MongoDB. I hear more and more horror stories of a team that realy thumped the MongoDB, only to hear they've ditched it completely in favor of PostgreSQL.
Personally speaking, I'm surprised how good PostgreSQL is and I realize that a lot of the reason we use a certain DB is because of marketing. Had I know about PostgreSQL before MySQL I would've never even made the switch.
I'm one of those - after almost three years with MongoDB, I left it behind when I formed a new start-up using PostgreSQL.
I have zero DB issues now, and all the MongoDB experience really worked for my employees as they now work full-time on it at a dedicated MongoDB provider, so win-win.
Personally speaking, I'm surprised how good PostgreSQL is and I realize that a lot of the reason we use a certain DB is because of marketing. Had I know about PostgreSQL before MySQL I would've never even made the switch.