LOL His is not a diesel, it's gas. The high performance version...

Panda may still have a good point. I have installed a dozen different spring/shock/strut combinations on my tacoma 4x4. Based on that experience I can tell you that slight changes in spring rate and shock valving can make a big difference in performance. If the Bilstein shocks are valved to complement the mercedes springs and the KYB's are not it can make a big difference. Ride quality is very subjective. If you are on a budget I am sure the KYB's will work. You may even prefer the ride. Based on what I have read it sounds as if the bilstein's are the best bet if your goal is to maintain the stock ride. New KYB's will be a huge improvement over worn out shocks. They just may not provide the ride/feel the mercedes designers where shooting for.