These claims are not false, however, a solid mass flywheel with the correct SPRING CLUTCH PLATE DOES THE EXACT SAME JOB.
Manufacturers and designers of the DMF don't ever mention that a standard type flywheel and clutch (solid) has damping properties and concentrate on telling the public how the DMF does such a good job.
I personally hate it when they don't compare the design to existing designs which also work - and are much simpler to produce and are more cost effective.
The only difference being a solid flywheel clutch doesn't damp at the same rate and has a far lower failure rate. This doesn't mean you will be destroying the gearbox by doing the conversion, it means you MIGHT get a little more engine noise if you like driving in super low RPM and like doing hard engine pulls from low RPM's. This is the reason why DMF's fail - a solid one will not fail because of this and will most certainly last a lot longer.
When your DMF fails you run the risk of clutch failure.
When a solid flywheel fails - wait - SOLID FLYWHEELS DON'T FAIL. They can burn out if your clutch fails, but thats the same for the DMF.
Advantage - Solid flywheel.
Some people will change their DMF for a solid only to be stung by the cost of the clutch plate. Do the maths first.
If you plan to keep the car for over 5 years and you are at the point of replacing your DMF, I would consider the conversion seriously.
A lot of people selling the SMF will make a massive markup on the clutch plate simply to make up more profit for not selling a DMF so shop around - if the price is good enough, buy 2 plates so you are good for at least the next clutch replacement!
This will essential convert your DMF to a solid with the welds. Please get your welded flywheel balanced before you refit to avoid the characteristic juddering on idle and high RPM.
Always check the release bearings are in good condition, and if you have the hydraulic release bearing, please install it in the compressed position to avoid failure when re-fitting and bleed it once the gearbox is bolted to the engine.
I have seen people who have replaced their DMF's with solid and then complain about a rumble when the car is idling and the noise goes away when the clutch is pressed. Classic mistake of neglecting a small part in the path of saving money.
Zndmotor is professional on the DMF conversion--Solid mass flywheel since 2008. Now we are successful on the Mitsubishi 4M41, Nissan Navarra, Ford transit, VW, Audi, Peugeot DMF flywheel.