I couldn't find the mbshop thread, but did stumble across this:

http://groups.google.com/group/rec.autos.tech/browse_thread/thread/25fd7e927f06ee65/c5e9f3b508a367d7?lnk=st&q=Do+Inline+6+cylinder+engines+last+longer+than+V6+engines%3F&rnum=14&hl=en#c5e9f3b508a367d7