I put a Quaife (LSD) in my for-competition-only Porsche 914
, and it cut my lap times by 5%, so LSD's are semi-mandatory in racing, but you shouldn't really drive around corners at 10/10ths on the street . . . regardless of whether you're in a MBenz or not.
Putting a LSD on a non-AWD/4WD car on the street is in the same league as substituting carbon fiber parts. The logic goes, "Racers have them, racers are cool; if me have them, me be cool." . . . I don't think so.