My opinion is a gray as close to black as you can get...
The only thing you are trying to do is break up the lines on the mask,only so it doesn't look like a black blob when photograghed...
When in person or proffesionally pics are taken there is no need for the two colors,When lighting is correct or a newer camera with all the filters present straight black looks good,but people with middle of the road cameras or picture phones wont be able to see the detail...
I thought long and hard before I painted my C/A with the two tone,but I costume with mine so it works better two tone.
For display I guess with the right lighting black would look good.
