Ruby on Rails or Ember.js with Rails API

Hello Experts,

I have been developing with Ruby on Rails for 4 months and I just
finished my first app (the link below).
For my next app I thought about using the open source project Discourse
that uses a lot of Ember.js for the App and Ruby on Rails as backend
API, but I am skeptic about this as I really LIKE Ruby on Rails, I would
like to work on the Backend and I have some Angular, Jquery, HTML, CSS
skills that I would like to sharpen, while learning also SQL and some
Backend staff…

My question is if Ember.js is really useful, as when a JS Framework is
used in developing a Ruby on Rails App, ofter we are speaking of a team
of developers and consequently some will be taking care of Front End
while other Back End. I would like to be in the Backend team, so I think
that the best approach for developing my Apps for now is only using Ruby
on Rails, but I am a noob and I would like to receive some advise.

https://barteringapps.herokuapp.com/

Thanks a lot
Fabrizio Bertoglio