I don't back-down on Moorings Balls, but I do dive them and inspect the hardware as far down as I can snorkel. One warning... sometimes sea-lice live on the lines connecting the ball to the bottom, so I would not recommend rubbing against them. Sea lice bite!

I do back down on an anchor each and every time... usually around 1800-2000 rpm. Then I dive it to see how well it's set.

These precautions have been adequate in 34 years of cruising the USVI and BVI.