I'll tell you what I have seen with black sand...
If you stick with a major manufacturer with an established history, such as CaribSea, the quality of the sand should not be an issue.
Some have found black sand to include magnetic materials, which can get caught in a magnetic scrubber and scratch your glass. I haven't seen this for myself, though, so I can neither say it's true nor untrue.
It appears dirtier more quickly than the lighter sands, so I would want to see an aggressive siphon/vaccum regimen if you go this route, one that gets into all the tricky areas.
Hope this helps. I could be wrong about all this, but it's just from what I have seen, not scientific by any means.