Now that is certainly a scientific sampling! I've seen Lehmans, Cummins, Yanmars, MANs, MTUs and Cats smoke heavily at start up, and many of them continued to while underway so should I suppose they all do? Not! There was a comment on here recently about Cummins requiring early rebuilds, I guess because some guy new a couple that did.
The problem with Internet forums is there is so much hearsay, or based on very limited observation, they are really only good for a small piece of the triangulation needed to get to the truth about a particular subject. I've learned a lot from some forums, but only when verified and coupled with verification from other sources that have the bonafides, not because they say so, but by references and direct experience with their work and/or their boats. And, ultimately, my own experience on my boats as in "how'd that work out?"
You've got a cadre of potential candidates lined up now. Time to see for yourself if any make sense for you
, have to judge each actual boat on its own merits and how it fits you
. As for the engines, don't make any generalizations, if you see a boat you like a sea trial and then a good engine surveyor will tell you if the engine is any good.