Early TD5's had a recall on flywheels, they were cracking and some had broken up. We changed no end.
I had a 5cyl petrol Audi the engine was really smooth and had a solid flywheel, I know it's not a diesel. the point is 5cly engines are not out of balance though TD5's are a bit lumpy compared to a Volvo 5cyl diesel.
A friend has a Disco 2 with a solid flywheel, I have driven it and wouldn't have noticed if he hadn't told me.