The high gas pressure de Carbon type dampers used on Mercs usually maintain their damping characteristics until end of life, which is commonly signaled by major oil leakage. My RF strut failed about ten years ago creating a obvious oil puddle. I bought a replacement from Bilstein who makes them for Mercedes, and it looks and performs identically including black paint rather than Bilstein's typical yellow paint.
Speed bumps are a poor way to test damper condition because they vary so much and they are designed to force you to go over them very slow or cause an unpleasant shock.
The best test of damper performance is over the road, particularly a wavy road. If the body does not float and wallow around at normal speeds the dampers are probaby okay.
The front strut dampers have a rubber jounce bumper concentric with the shaft and hitting this could cause some rubber shavings. You can probably see the jounce bumper if you lift the dust shield and peer up into the shock tower. If you can reach it will your hand or a tool you can pull it down to the bottom of the shaft as it free floats on the shaft, but compression of the strut to near maximum will push it up to the top where it will stay.
I recently pulled my front struts to replace the disintegrating dust shields, and I also removed the upper mounts for careful inspection. Both the upper mounts and jounce bumpers appeared essentially new, so I just replaced the dust shields. My 201/2.6 only has 75K miles. I do have an occasional "clunk" that appears to originate at the LF when the suspension goes to near full rebound with the steering wheel turned such as exiting a steep driveway, but I couldn't find anything that appeared to be the culprit
I suspect that your front struts are okay.