As I shop for clean, low-mileage W210s, I've noticed that W211s with similar miles are as cheap, or even cheaper(!), in many cases. Is there something I'm missing? Or is it simply that W211s are known to have more issues, i.e. post-Bruno Sacco era design, and thus generally less appealing?

 

W211 have very well, and annoying issue. Instead of asking here, which is for W210, you may want to visit W211 forum.

When it comes to W211, I'm not expert, but they have few well known issues. Some are very expensive, some are just annoying.