Does the Y.S clearly out perform the O.S series for pattern flying ?

The 1.4 OS is about equal to the YS 1.4 and proably a bit more popular amongs't pattern flyers. In fact I think the fuel injected version is more popular.

Japenese technology is not better than the US. Just the labor rate is lower. The rusult was that the US companies lowered their quality to compete. Now US quality is better, but the price a tad higher. But the general consumer has yet to notice. The Jett's and Nelson's are probably the best R/C engines out there period. K&B and Fox make excellent sport engines, though Fox has some carb issues with the larger engines.