Of the mongoDB projects I've been involved with, I've always wanted to do large complex joins and filters which was just didn't perform as well as relational databases, and there is no support (as far as I know) for geo-coded data.

That's why I suggest it's good for prototyping, maybe it will work for some projects long-term, but I don't think it's the norm as mongoDb would suggest.

However, most prototypes don't end up as successes, so that's where I figure it's worth the switching cost once a go-nogo decision is made.

There are many drawbacks when using MongoDB, especially in the development time department: http://cryto.net/~joepie91/blog/2015/07/19/why-you-should-ne...

It's a completely fallacious argument. Using MongoDB doesn't save you time, it just shifts the effort towards a later point, where it will require several times as much effort to fix shit, which may not even succeed and you may end up with corrupted data.

It's really not worth it.