What are the actual pros/cons of the ball/socket systems?

There have been several designs/brands over the decades, I know one guy who still uses (and swears by) the old Sail Safe system. At least, I think that was the name. There's also the Bethwaite, and now this:

http://www.nauticexpo.com/prod/allen-brothers/product-29493-450885.html

Again, what is the downside of these? And, do those downsides outweigh the risk of our current hooks?

Mike