Juma comes to mind it is available in black, if you want a nice finish good hitting ferrule, not to hard not to soft. I am personally really enjoying my Tiger fortis shaft and that ferrule/vault plate is bright orange. The orange gives great sighting feedback compared to the light reflection usually given from carbon shafts with short vault plates, also the fortis shaft weave and finish reflects way less light and is the darkest "black" shaft I have owned to date.
But back to your question, I know a few people have preferred black ferrules in the past due to the contrast on the cue ball. One pro comes to mind prior to the carbon phase, Mike Dechain, I recall seeing him play with a black ferrule on a couple live streams. I could be wrong, Honestly I think it comes down to user preference, And when I think of it I think a very shinny well finished black ferrule may reflect the most light! If anything you'd want it dull " Flat " finished if it were about line sighting.