I've been using Yale 11.7s and they are superb. Today I used Tangent which is the orange version of samson voyager 11.8. It was perfect too.
They are a little difficult to feed into the zigzag so a thicker rope would make that even more difficult.
It is a superb device.!
I don't think it had anything to do with race. It did have a class aspect to it though. It felt like if I lived in a rich area I could swing my children from a tire swing with a crappy rope and nobody would complain. If anybody did the police and the quasi-governmental child protection service...