Just out of curiosity, and believe me im not fighting you on the issue, but why would an engine need the load on it when breaking it in? The whole idea of the break-in is for the piston to seat into the sleeve via heating and cooling, so load or not, the task gets accomplished, right?

Also, what negative effects have happened from breaking in a boat in a bench?
After my break-in on a bench, I pulled the piston and sleeve and everything was squeaky clean. I never over revved the engine, just short blips to clear it out.

Again, Im asking this out of curiosity, as Ive not heard of negative results from breaking in an engine w/o a load on the crank.