I have not heard of Dave Pascoe to make such a universal negative statement of this engine.
The Cummins 6CTA8.3 is a bullet-proof engine if properly loaded, run and maintained, capable of over 5,000 hours before a major. At WOT with a full load of fuel and gear, they should reach a rated 2600 rpm at a minimum. If not, either the boat is over-propped, the bottom is fouled, or the engines are not getting enough fuel or air.
A over loaded engine's life span can be reduced by 75-80%.
For the best experience and advice, call Tony Athens at Seaboard Marine 800-200-2628. Or visit their web site at
http://sbmar.com/
Another great resource is
www.boatdiesel.com
Evan