Thanks for taking the time to reply. Here are the answers to the questions:
1. Yes, the springs, shocks/struts, strut mounts, etc. all were brand new, and the springs were not cut.
2. I thought so, but since I replaced everything at once I had to indicate that.
3. I am not sure if I can check for that myself. I will jack up the car, put it on stands and see if I can see anything. Considering the springs were installed at an independent shop last week, the shims were replaced today by my regular MB service shop, and the problem persisted, I can only hope that they did install the springs right. Perhaps I should have rented a spring compessor and try to install these myself (no time with two small kids, though).
4. I did that only because of what I read in section 40.03 of the maintenance manual. It suggested that there is indeed a height difference tolerance between left and right, and it may be as much as 1.5 cm. It also suggested that shims of different thickness may be used. So, I followed.
As soon as the mechanic who originally installed the springs comes back from vacation, I will go back and ask them to check for spring tension, perhaps swapping the left and right to see if the height difference also switches sides.
The current rims are genuine AMG 17x7.5 ET37 from Tire Rack (Style 209 double spoke). I noticed posts at number of forums that applied the same modification to 300E/E320 (inc. the same wheel setup) without any rubbing or problems. Perhaps this one will turn out to be a 400E-specific problem.
If the top spring perch is collapsed, shouldn't have the installer(s) noticed and raised it as a concern? Perhaps not. I will ask that question. Side bar - if the top spring perch is compromised, what would be the remedy?
Thanks again for your time.
Cheers