Its always hard to say without feeling the fault Simon, but i would say if there is alot of pulsing through the clutch pedal i would be going more with dual mass.
Another pointer for dual mass is if you listen to the engine as you turn the key off sometimes just as the engine comes to rest you get a "chacky chack " sound ...best way i can describe it , it the noise of the excessive play in the dual mass unit .

Hth Lee