downunder,
Actually no, you're not the only one silly enough to test thoroughly. Chuckle.... There are at least two of us.

And I found exactly the same thing as you. And btw, your "contradictions" aren't even close to being contradictions. And there also isn't a word in your posts that is un-cordial. Some people can't read too good, don't understand complex stuff very well, and are less than cordial from the git-go. The internet is an amazing and often silly place. It's funny that you've given good advice to two different people, yet are attacked by someone who missed the point (twice), and then a third guy jumps in and paints you both with the same paintbrush.

I've also found that 4-cycling a plain piston engine during running-in ain't a big deal. Heck, it isn't even a deal at all. The idea that 4-cycling "squeezes or whatever" or beats anything to ruin appears to be one of the myths that has really gotten blown up by some of the more excitable, less experienced, wanna be experts. Hey, fuel flow cools. And 4 cycling still "allows" the mating parts to rub against each other and locally heat up. And an engine at say 8,000 rpm "feels" almost exactly the same "pounding" at 4-cycle as at 2-cycle and that "pounding" is way far less than at 12,000 and the suckers are designed to stand even higher rpm. The 4-cycle to 2-cycle break is an excellent "tool" to give you an idea about your gas mixture into the engine. And about the only thing the 4-cycle does for/to you is greatly slow down the break-in. But it's extremely sensible to use early on to make the break-in safer for the components. None of this stuff is simple and isolating the 4vs2cycle issue out as a make or break detail is actually sorta dumb. but what the heck....

BTW, I was tearing down motors after break-in and a bench test because a buddy and I were making our own pistons to try different timing, tolerances, shapes, weights etc etc. And we usually measured off (and visually judged) the sleeve and piston before break-in, after break-in, and after testing.

Aldrich was a heck of an engine man. And his observation that CL flyers didn't encounter the same problems as R/C flyers was extremely telling... and subtle.... CL guys ran more oil... and more castor... and usually more than half the flight at 4-cycle... and our engines lasted forever (wanna buy a Johnson Stunt Supreme that still has decent compression after thousands of flights?), that is, when they were made of halfway decent metals... and seldom saw a lean run.

BTW, have you ever noticed that the first person in an argument who bleats about being civil usually isn't and usually gets shriller and shriller?