The arguments from WilsonFlyer seem to be supported by the solid evidence that lies just in our own backyards tools, where the break in is indeed simply not even mentioned at all in the user’s manual.
We don't know the tolerances used to machine the pistons and cylinders of our airplane engines, more likely and hopefully the 2 strokes model engine manufactures are using similar equipment and similar tolerances to manufacturer engines as HONDA, HUSQVARNA, JOHN DEER, etc do. If this is the case, then breaking in an engine is only mater of time, our engines are like plug and play device, just run it!
Only one observation and I think everyone can confirm this: after running the engine for certain period of time I have noticed a moderate increase of rpm (anywhere from200-300 rpm) the engine seems to be running smoother and cooler, all together gives you better performance, this is the break in we are looking for, right?
By the way and maybe few of us have really paid attention; as a point of comparison, I can not report the same observations in the last weed eater that I bought or at least I did not really care about it. In addition I think few of us have ever try to trace a weedeater performance by checking its rpms, go figure...