OK, I think there's some confusion here. The Dropoff is AT the mooring buoys. There may be boat traffic and you need to be careful, but if you're with a group of divers, a gaggle of flags tends to be more noticeable...safety in numbers, as it were. A boat bearing down is a scary idea. Can it happen where we dive? Yeah. Is is a regular thing? Not at all, be we tend to be careful. Also, weekends and holidays with really nice weather make the boat traffic heavier, so we're extra cautious then.
If you're uncomfortable, there are plenty of other dives...but for any of them, if you're in the water, boats may be too.
There's absolutely no truth to the rumor that just like other marine mammals you can often identify different South Florida beach divers by our prop scars...and I don't want to speak for Jenny whom I know and deeply respect, but she has had a few close calls over about a zillion dives. Like anything else, how much time you spend in the water affects your odds, too.
Let me put it another way...I'm not as experienced and only have about 100 or so beach dives in this area. Number of boats I've had to dodge? Zero.