I agree, it is possible that a better fuel quality in Europe, made this engines reliable in Europe and "rod bender" in America.
I have looked for opinions of this engine in European foruns and people say that the engine is very good (except the engine head that may crack if overheated).
I asked the question of the "rod bender" in a Spanish forum and no one have ever heard anything about that problem.
The answers of the users of that forum to my question were (translated):
"I have never heard that problem. 350 engine is one of the best mercedes diesel, it is very reliable,... It is a very good engine to do long trips in the highway; although it is not very fast it allow us to do big trips with all the confort of a w140 but with more mpg"

But the question is: Can the quality of the diesel make so big difference in the reliability of the engine? (for me it is hard to believe).

And other question: Anyone know the speed of gear changes without accelerating? Because I think that the last gear is entering very early: at about 36 miles. Is this normal?