I still like channels because they may be a net reduction in the number of concurrency primitives in use, which complicates quantification in the paper - their taxonomy is great, though. Channels have some sharp corners.
Reducing the number of concurrency primitives does not imply reduction in complexity. On the contrary in fact, I've seen the messes created by golang in large production systems. Here's a good article: https://www.uber.com/blog/data-race-patterns-in-go/