I have an SLK 230 Kompressor and it does have hard seats. Difference is I like it that way. When I drive my wife's Ford now it feels like I'm navigating a sofa down the highway.
Krycheck - go to these sites:
http://www.mbnz.org/forums/default.asp
http://forums.mbworld.org/forums/index.php
They have sub-forums for every kind of MB ever made. Lots of good info.