Balancing ALONE will give a smoother engine,m and one that is a lot more eager depending on how well it was baalnced to start with, but you WILL notice the difference.
I have never yet NOT had an engine balanced that was apart, and every single one there was a VERY noticeable difference, even on my automatic mondy engine.
The best treatment for long life/strength and fatigue resistance is CRYOGENIC FREEZING, whereby the components are frozen for 24 hours at around -280C, then slowly thawed, but not many places, over here that do this.
It is VASTLY better as it is not a surface teatment, but goes down to a molecular level, right into the heart of the component.
tabetha