Perspective,
Why reinvent the wheel. I'm not saying you should not attempt to build your own engine to suit your own needs, but surely you would build on lessons past.
I don't think there is anything wrong with trying to improve the wheel. eg Jabiru's excellent power to weight ratio.You just have to be careful and move quickly if or when a problem emerges.
Some
made by Continental and Lycoming have cost owners a disasterous amount of money and even cost some lives before those companies were forced kicking and screaming to rectify the problems. Lycoming's crankshafts and Continental's belled out cylinders come to mind.
RA