Im confused by this post?
Many factors play into the durability of the Pistons.
The Keystone design should be good for 150,000 - 200,000 or more miles. They kinda self correct themselves as they wear. Very neat design IMO. However, they put a lot of pressure on the ring land. More than aluminum can handle. Thus the steel insert in the Cast pistons.
The longevity of the Forged ring land is dependent on not only the time in the motor, but the pressures that the fire ring is seeing. I've heard of some people opening up the ring gap a tad to reduce the pressure across the ring and help reduce the pressure on the land.
So, your mileage on a set of Forged will differ from application to application.