I just changed my shocks with bilsteins after long consideration. I have over 200K mi on my 260E but the shocks pass the bounce test as described by repair manuals and in this forum. (When I push down on one corner of the car, it comes up and stops as advertised). When I had the shocks out, I pushed on the shocks (like an old bicycle pump) to see what kind of response I could get:
- The old shocks still had resistance when compressed but slow to rise up.
- The new ones (bilstein comforts) were a lot harder to compress and bounced really fast (quick acting?)
Based on my experience, after changing shocks on my other cars, most low end shocks only last 3-5 years (30K-50K mi) while the high end ones last about 100K mi regardless of bounce test. They can last longer but with a slower response rate. It's only a matter of taste at this point and what you are willing to put up with.
That's my two cents. Happy motoring.