Congrats on your wonderful car!
Conti is the major German tyre manufacturer
I don't think there is a specific answer to your question about a switch
from Michelin (except: don't worry about it); Merc uses various brands.
My old 190E originally came with Contis, and my 2001 CLK Cab came with
UK Merc dealers tended to prefer Michelins but could not do anything about
Somebody at Merc told me that the Pirellis (and tyre makes in general) were
matched to the car.
Make of that what you will. Some people may take the view that Merc buys
tyres in job lots and takes the cheapest batch at the time...
NB: To reply directly replace "nospam" with "schmetterling"