I read in CAR magazine about 18 months ago a report that Mercedes wanted to get away from supercharging, and instead use turbocharging when displacement wasn't enough.
The report stated - and I don't recall if it was a source from Mercedes or just a technical fact - that supercharging places weight up high on top of the engine, which is detrimental to handling. And that supercharging means high gas consumption whereas in turbocharging they can manipulate fuel usage better.

That article came out when the twin turbo V-12's were just hitting the market.

Then I remember reading an article in CAR some months later that AMG was continuing work on superchatging.