[vetrom]

Speaking as a sometimes Erlang developer: the ecosystem certainly isn't as universal as language $FOTM. That said, Erlang's concurrency primitives and runtime are second to none, and there is little that is more battle-tested in the industry.

Individually developers will be more expensive, but if you have a product that demands maximum leverage of concurrency (i.e. data-heavy api, whatever-in-the-middle services, multiparty real-time data), you will more than makeup the developer premium when you get to that point.

I havent hit Elixir yet, but it seems to make access to the Erlang runtime much easier. As far as SDKs/api, Erlang itself has primitives and libraries to build useful access to most APIs you can find. If you're worrying about what services you can access though, you probably don't need Erlang's features, at least not yet.