Back in May I replaced my rear shock absorbers with Sachs ones from a Mk7 Golf, as others on this forum had suggested. This actually made the rear suspension a little firmer but made a night and day difference to the ride quality at any speed. It made the car a bit more composed and settled at speed as well. Overall it's so much better.
Pros: improved ride quality, more composed
Cons: slightly firmer suspension
Vehicle:
Skoda Octavia
Mileage: 4800 km