Funny you mention this, I literally had my clutch and DMF replaced yesterday. The DMF replacement is preventative as the labour to get in to change the clutch is significant and it's not a job you want to do more than required. It rarely makes sense to replace the clutch without doing the flywheel at the same time if it's dual mass. That price sounds pretty reasonable, just make sure you get the genuine stuff with warranty etc. Assuming fitting is additional? It cost me £350 for mine to be fitted at my local indy. As I track my car on a semi-regular basis and it's been mapped, I decided to go for a Helix organic clutch to replace the OEM one, you may want to consider the same if you've got any mods or are planning on any.
My DMF was totally knackered and the symptoms were clutch slip under full throttle but with no burning clutch smell and a metallic rattle at idle which went away if you pushed the clutch pedal in. Sounds kind of like someone spinning two metal plates together, hard to describe. Both symptoms were definitely worse when the engine was hot and it seems that heat is one of the things that really kills the DMF's in addition to wear and tear.