Whilst doing the spring and damper testing for the modified steering stem set ups I was testing dampers back to back over a regular route which included basically all types of road surface although it wasn't a long distance.
Before changing to the eccentric/concentric bearing conversion the best I found was Thornton's but this was only marginally better than the AVO, at a much higher cost, the next pair which were about the same as each other but not as good as the AVO were the Armstrong and the Standard damper, the worst I found was the Koni, I tried three of these just to make sure I hadn't a rogue one, basically it didn't react to small movements at all and so if the surface was small corrugations gave a really rough ride, interestingly all gave about the same performance over speed humps and under emergency braking.
Chris.