Hi!
I am not sure where Cayman Brac is, but i have been at Cayman islands, and I can only say that the diving there is superb! Clear water, great sites with tons of fish, turtles, stingrays sharks etc.
The only bad side is the price. Food, drinks and so on are extremmely expensive!
Donīt know if you could use my reply ;-) ?
Best Regards
Mikkel