Fewer mutexes isn't necessarily an advantage, there will be far higher contention on that single mutex. Channel writes also require a lock.
One to write, that's used for writing only, not both read/write as in the published design.
Edit: it's a variation on the following, but for ReverseProxies, not worker goroutines http://marcio.io/2015/07/handling-1-million-requests-per-min...
Fewer mutexes isn't necessarily an advantage, there will be far higher contention on that single mutex. Channel writes also require a lock.