Multiple channels in Phoenix/Ember app

I'm building an app in Ember with a Phoenix server back end. I'm very new to Phoenix but am interested in the channels feature.

I'm curious how well channels scale if you connect to lots of them at the same time. As an example, consider a WhatsApp clone where I want to know if any of my Chats are updated with a new message. Ideally I'd like to subscribe to one channel for each Chat, but will this still work if I have 50+ different Chats all connected at the same time? Or should I architect the app to have one channel which sends updates for multiple Chats?

Thanks in advance