I just put a set of Pirelli PZero Nero M&S tires on my 4Matic and couldn't be happier! They are both quiet and comfortable. You might want to do some research on tirerack.com. Lots of charts, reviews, etc.
Yes, so far they've been just that: quiet and smooth. They handle real well on tight turns and work hand in glove with the car's suspension. Time will tell, but so far they've exceeded my expectations. I highly recommend them. I paid $605 for all four. Probably could have got a better deal, but they're Z rated and have a good reputation.
I've been riding on these tires for the past 36,000 miles and have been very happy thus far. Excellent snow traction when new. Rain grip and handling has been excellent. I have had one inner sidewall crackup all around the wall, but I feel from research that it was due to underinflation. Been riding on that tire for a while with no problems.
Overall I am very happy with this tire and would re-purchase. I have these tires in an 18" size.