I say turn the rotors. I changed the rotors on my Nissan Quest, the G20, and my 93 300E. I used Brembo on the Nissan and the G20, and factory rotors on the MB.
I always take the new rotors to my local mechanic and have them turned before I install them.
I learned this from my father, who was a mechanic for Unocal (corporately, not a gas station, worked on drag racing cars, etc.) but our experience has almost always been that rotors are not true out of the box, even when brand name. I've argued with people and mechanics about it. Sometimes they even get a little hostile with me and refuse to do it. You know, sacreligious turning new rotors.
After seeing the rotors needed turning, they always apologize to me. Blows their mind.
I don't know why they can't make rotors absolutely true from the factory. I just know they don't.
2001 E430, Bourdeaux Red, Oyster interior.
1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron".