If you think the harmonic balancer design is bad on the V-6 engines, you should see the HB design on the 1.8 L 4-cylinder Kompressor engine. The HB design on that engine resembles a "Hockey Puck" that is made of hard rubber with a groove to retain the serpentine belt. On mine, the belt slipped off the HB before the car reached 20,000 miles on the odometer and tore up the HB and several electrical sensors. According to the service advisor, they have seen this issue before.

All I can say is, that in retrospect the HB balancer on your vehicle is now a quality part based upon Mercedes new designs. I also was displeased the the HB on my 2000 ML320 but this design now appears good to me based upon what I now see on my 2003 C230K.