My old dive club has a 5.8 Destroyer that is now 14 years old and, when new, was fitted with a 150 Mariner simliar if not exactly the same as the one shown.
Because it was a dive boat the extra power was needed to carry 8 divers and kit but when it was empty it really could shift, 50 knots IS a fairly realistic figure
They still have it athough I know it was fitted with a 4 stroke motor a few years ago.
I don't want to start the "my boat is better than your boat" thing as nobody has driven every boat and there are always issues or things one boat will do better than another.
.....BUT of all the boats I have ever driven the 5.8 Destroyer is the best handling hull I have tried so far, I never get tired of playing with it.........