Derate implies a lower Vmca is one of the factors to keep in mind when using it.
As far as i know you can get the same thrust reduction in two ways ( i am exagerating a little bit), for example 26K rating with 50 deg and ATM = 24k with no ATM as long as you the resulting N1 has the same value. The thrust delivered by CFM engine is a direct proporcional with N1, 3% N1 reduction = aprox 10% thrust reduction.
Regarding the limited life parts i have no ideea.