I started playing with Erlang and Haskell around 1998. Wow. Over ten years ago. I recently came across a post that may be my first on Erlang. It's to the Squeak list, suggesting Erlang might be seen in the same "message-passing" family of languages as Smalltalk. Someone had written, "I would like to create an application which runs seamlessly across multiple machines and platforms, but it's too hard because the communication and coordination is a bitch.". I replied...
Another approach is the simple message passing approach. This would be interesting to consider, given Alan Key's recent email to this list about "messages" vis-a-vis "objects".
Consider the programming language named Erlang from Ericsson. It is a concurrent and distributed language with no shared memory. All communication is by sending high-level messages. Receivers can pattern match on messages with time outs, etc. What Erlang calls "processes" can be linked to each other for high level process control and reliability.
There are several production-quality communications programs built with hundreds of thousands of lines of Erlang code, so it seems to have some practicality, which may meet the "lots of gain" requirement. The simplicity of it seems to meet the "little pain" requirement.