More diverse is easy, Go is opinionated about its concurrency.
"At least as easy" is a flaming lie. The diversity alone makes it impossible but beyond that:
* when you look for concurrent go you're introduced to 3 constructs (`go`, channels and `select`) and you're off to the race having barely learned the language
* when you look for concurrent haskell you're directed towards the corresponding paper, "tackling the awkward squad" and a world of Async, MVar, ThreadId, STM and various types of Chan, and at that point you still can't write a line of concurrent haskell
Like the_duke I don't enjoy Go, but with respect to dead-easy concurrency the only language that's in the same ballpark is Erlang (and it's similarly boiled down to a complete lack of diversity — though a different model than Go's — and three basic constructs: `spawn`, `receive` and `!`).