The 838 provides significant cost savings in piping and labor when used instead of a conventional parallel set or prefabricated header design.  It costs less than a large orifice regulator and separate relief valve and piping, and provides safety advantages as well.  Using two small orifices rather than one large orifice provides better control of outlet pressure over a wide range of inlet pressure swing, as well as reduced overpressure build-up in the event of failure of one small orifice.