My DMF is absolutely knackered. Its rattling around like mad and is just generally stuffed.

I have been having a read up on Solid Mass Flywheels as an upgrade for when i change it.

Has anyone fitted a Smf and if so what are the advantages and disadvantages in comparison to a Dmf?

Fitting a smf is not an upgrade, it's just an alternative. It's almost standard practice on transits, but I don't really see an advantage on most cars. Presumably you don't drive 40k miles a year (unless you are a taxi driver), so a new dmf should last a few years. A smf often results in a less smooth drive in terms of vibration etc. (not always though). The main advantage of an smf is that you never need to change it again. Basically that means for the average person you can save £300 once every four years. Will you even still have the car then?

There are lots of horror stories doing the rounds about damage done by smfs, personally I think they're nonsense. Dmfs are fitted to smooth out the harshness of diesel engines that's all. You pays your money and you takes your choice.

I dont do 40k miles a year but i will be doing quite a lot but that will be motorway miles.

In short then, the Dmf gives a smoother drive and keeps it as per ford recommend.

I wont still have the car in 4 years time, hopefully will be looking at a replacement in 2 years time!