II think running two engines side by side is not meaningless, but not of much value either. Unless the clearances were checked before and after running. There are many fits, tapers, and tolerances manufactures can chose from and an engine made with little taper and a looser fit or harder materials may show little or no difference. I know that the LA engines are good runners while running at a full four stroke. If you follow the manual verbatim you will most likely be breaking the LA in at a full four stroke, and they seem to do well that way. On the other had if you break in a K&B 48 you will have to heat the cylinder up just to flip the prop. Four stroke that one during break in and I could see breaking the rod during a cool day. Like after an icy gust of wind. I am sure the possibilities run the gamete so I recommend following the manufactures instructions.