Yes, I've used the black version on a couple of my ukuleles. The ball ends had to go, but that's because they don't work with many styles of bridge.
I like the sound and they didn't seem to take quite as long to settle as some nylons, but on one of my sopranos I had to remove them because the intonation was way off: replacing with fluorocarbons fixed that, although at the cost of the lovely vintage sound.