Did I miss something?  Betarigs is not using stratum at all, but oldschool http / getwork protocol.  Is there a reason why?  I think this is because mux based his work off of stratum_proxy which exposes http to the miners.

Stratum would be far more efficient with less latency.  In this model that would be important because the pool is proxying for another pool.  If the receiving pool is a coinswitch pool, latency matters big time.  JSON RPC will be faster than http setup/teardown.