Brian has added the Noise test result
http://www.the-digital-picture.com/Reviews/Camera-Noise.aspx?Camera=1140
and his comments on the Noise performance on review page
http://www.the-digital-picture.com/Reviews/Canon-EOS-6D-Mark-II.aspx
He seems to be convinced that noise performance of 6D2 is very comparable to 5D4 although later has higher resolution
Vs 5D4 @6400
http://www.the-digital-picture.com/Reviews/Camera-Noise.aspx?Camera=1140&Test=0&ISO=6400&CameraComp=1074&TestComp=0&ISOComp=6400
and also 6d2 @6400 seems to be a bit better than 1Dx2 @12800
http://www.the-digital-picture.com/Reviews/Camera-Noise.aspx?Camera=1140&Test=0&ISO=6400&CameraComp=1041&TestComp=0&ISOComp=12800
http://www.the-digital-picture.com/Reviews/Camera-Noise.aspx?Camera=1140
and his comments on the Noise performance on review page
http://www.the-digital-picture.com/Reviews/Canon-EOS-6D-Mark-II.aspx
He seems to be convinced that noise performance of 6D2 is very comparable to 5D4 although later has higher resolution
Vs 5D4 @6400
http://www.the-digital-picture.com/Reviews/Camera-Noise.aspx?Camera=1140&Test=0&ISO=6400&CameraComp=1074&TestComp=0&ISOComp=6400
and also 6d2 @6400 seems to be a bit better than 1Dx2 @12800
http://www.the-digital-picture.com/Reviews/Camera-Noise.aspx?Camera=1140&Test=0&ISO=6400&CameraComp=1041&TestComp=0&ISOComp=12800