Well, I'm still struggling with Ruby when coding Discourse plugins. I'm OK with Javascript; but cannot get my head around Ruby as a server-side language after years of PHP.
Today, I found this PDF file, which helped a bit (but not as much as I would have liked!)
Rails for PHP Developers
Derek_DeVries_Mike_Naberezny-Rails_for_PHP_Developers-EN.pdf (5.1 MB)
Must be just me, but I thought PHP was great for building web apps and cannot get my arms around Rails for some reason.
Those days are far behind me now, and I am easily surfing with Ruby in both Rails applications and Discourse plugins.
In fact, I find Rails much easier and faster to develop web apps than using PHP and doubt I will ever build another PHP web application after building a number or Rails applications this year.
As far as Discourse plugin development, I'm fine with Rails - smooth sailing for sure; but I have yet to become an EmberJS fan 
I think it is safe to say that if Discourse did not require EmberJS, I would not even consider learning or using Ember.