Wiseco states "All Wiseco rings (that means XA's, XC's etc) can be used for cast iron, nickel ceramic platings (Nikasil), boron composites and Electrofusion bores." The only exception is chrome plated cylinders which must use XJ rings. XJ's are cast iron. JE simply says do NOT use chrome rings with CHROME bores. You fella's can check online the materials etc for the JE and Wiseco rings....they basically all come from the same suppliers.
For example..Busa's are Nickasil and they use XG's or XC's. If there was a problem with the Wiseco and JE XA, XC, XG rings Millennium would have said something years ago.