Going from "tens of thousands of hours" to something that needs serious attention at 700 hours is quite a tradeoff for the the luxury of speed.
I suppose "any" engine gas or diesel will have the same peril when you run up the power rating, sure would anticipate that with our 427 gas motors or any other motor for that matter, if you ran it up to 1 horsepower per cubic inch. Some of those would never make it to the 700 hour mark, and some may only make it to the 7 hour mark depending on how they were used. Assuming the pistons and connecting rods are upgraded to take the punishment, the generation of higher power also puts a huge wear factor on bearings and I suspect also on rings and cylinder walls.
Along with the additional power comes additional heat, and this is what most likely contributed to the destruction of some of the motors we are aware of that have come apart after rebuilding (those that deviated from stock marine specs). On one example, the 427 powered 47 Commander, PARAMOUNT, had engines rebuilt and they came apart not once but twice. Although I never really heard the specific outcome of the malady, it was apparant that the intakes, carbs, and pistons were not stock, and therefore I suspect the compression ratio was not stock either. The result was more power, and the captain noted the fact that the boat seemed to move better and commented on the "more power" issue, but shortly thereafter pistons melted and connecting rods broke. It was not a pretty sight (or sound). Part of the problem was (we think) the use of
hypereutectic pistons rather than forged pistons, the hypereutectics are high in silicon and more brittle, and just will not take the punishment that forged pistons will. The engines seemed to run fine on the dyno, but when put to the task of pushing a 47 Commander, they generated so much heat and internal stress that they came apart.
Here is the video of a 427 breaking a connecting rod and melting pistons, not a pretty sound. Marine engines used in cruisers should be rebuilt to the stock setting, becuase they get the same duty as a dump truck running uphill fully loaded.