Theres a guy on theMalibucrew.com who just lost a flap & sucked an engine full of water. It may be precautionary, but it's there for a reason. And the consequences can be really bad.
Vapor lock is a whole different thing than hydrolock. Vapor lock is a fuel problem. Hydrolock can make your engine throw a rod or crack a piston.
As for FAE or turn down tips..... take a cup & turn it upside down. Then push it down on the water. Does the cup fill with water? No, and FAE won't allow water up the tube either.
(Message edited by bill_airjunky on July 27, 2009)