SMF is soild metal so cannot in therory break but rattle when installed in your clutch/gearbox.
DMF is two metal discs held together with springs which remove the vibration from the gearbox and shift mechanism. Since diesel cars produce a lot of torque the DMF has been known to pull itself apart, you can tell when this is happening as you will get a vibration in the car since the DMF is no longer doing it`s job of removing the vibration. Millions of cars are fitted with DMF`s some of which break like any other car component, trouble is you only hear about the ones that break not the other 99.9% of the millions of cars that don`t get a problem with the DMF.
DMF is two metal discs held together with springs which remove the vibration from the gearbox and shift mechanism. Since diesel cars produce a lot of torque the DMF has been known to pull itself apart, you can tell when this is happening as you will get a vibration in the car since the DMF is no longer doing it`s job of removing the vibration. Millions of cars are fitted with DMF`s some of which break like any other car component, trouble is you only hear about the ones that break not the other 99.9% of the millions of cars that don`t get a problem with the DMF.