I can't remember what DIN stands for, but it is simply the setting of the spring tension. Whenever the force of your boot on the bindings exceeds the force tension of the spring, the binding releases. So, the higher the DIN, the higher the tension on the spring.
If a 4-12 DIN range binding is set to a 10, it is proportionally putting more tensile stress on the spring compared to a 10 setting on a 8-18 range binding. So, it is true that the spring in a lower range binding will wear out faster than a higher range binding. However, the release and performance SHOULD be the same if the bindings are both relatively new.
I hope that was helpful.