Now you are mistaking and/or mixing expertise with reliability.
A high performance engine is not for a beginner, because the window of operation is much smaller and the engine is unforgiving if operated outside that window. Yet in the hands of an expert flier the engine performs without a hickup.
Those that make it to the chequered flag in high demand situations are reliable AND powerfull, handled by experts, not unexperienced rookies.

Your question indeed should have been," for a beginner, which engine is better"
The YS beats the OS every time IF YOU KNOW HOW TO HANDLE IT!  IN THE HANDS OF THE ADEPT, THE ENGINE DOES NOT LACK RELIABILITY.
In the hands of a beginner, it is pure misery and a sorry investment.