We would live probably 30% shorter. More self healing, more replication, more offset in DNA means you reach eldery quicker. Every replication event contain tiny chance of mutation as well.
Cancer comes from mistakes in the self healing process and erosion of the DNA chain. I think it's implicit that 30% more self healing means "30% more self healing correctly" and not "30% more healing for the same amount of injuries". I think the former is also analogous to the road example.