With the diesels I keep it stock, espeicaly with the SDL. I don't want some MB newbie mixing up a rare SDL with a run of the mill SD.
If I had say a 500E or something that is a bit of a wolf, I'd take the badge off the rear, leave them guessing.
I always thought it would be a hoot to put E350 4Matic badges on the rear of an E55!
Some guy in a Viper or Z06 would be pounding the dash of his car pissed off because he can't pass a V6 MB.