Machine monkey said:Ok i dont have a full grasp so this might not be 100% correct.
But my understanding the CDV is to prevent harsh and sudden shocks causing damage to the DMF. From surges of power from say the clutch being drooped or poor gear changes. Its sole purpose is to protect the DMF from shock.
Exactly right

This is another "can o' worms" topic. Ultimately your car your choice. The effect on an M is apparently less than the non M, but it doesn't take too long to adjust to driving style.