I think contrast when I think Galway - it seems by far and away the prevalent choice for that boot, and it looks awesome that way. Consider dddrees' recent acquisition - wouldn't be as sharp in all medium blue or all midnight blue. Plenty of choice in predominantly monotone derby boots from EG - Alderly and Nevis, for example.
Not saying a monotone Galway would necessarily be a bad thing. I actually like the idea of one colour shell, but grain on the shaft for a sublte contrast in texture.