> Besides, erlang definitely gives you new perspective in building large scale system; supervision tree (let it crash), the actor concept, message passing, preemptive vm, built-in distributed erlang nodes, the repl, hot code swapping - any much more

Can't emphasize this enough. Programming in Erlang will enable you to build novel mental models, useful beyond Erlang/Elixir.

Moreover, Erlang is a small language, and once you get past the unusual syntax, pretty easy to learn.

I work on a large scale production system in Erlang on a day to day basis; feel free to email me if I can be helpful in any way.