tech stack proposal

What do you guys think?

I would like to learn a new front-end framework -- hence wanting to give Ember a try.

I was thinking about using Rails -- but I have too much velocity with Python at the moment -- but I am open to it (I do love using mongoid)

Last -- I was also considering postgres.  I think it would be cool -- if we could offer super easy one click Free deployment to  heroku.  And we could leverage there free postgres instance.

But I really love mongo.

Discuss!!