Maybe a bit late, but I have a recommendation as well.

Noise and vibration may come from wrong tyre wear (as we call it - the tyre gets worn in the shape of a sprocket-wheel and that makes the noise). Tyre wear on the 4M front axle may be impacted by worn rubber parts on the transverse control arm. Im talking about nr.59 in the picture.


So, swapping back to front would solve the problem for a while only until the wrong wear sets in.
I've had a 4M W210 for more than 3 years and I have a set of winter tyres that were silent at first but now they make the car sound like a dive bomber of WW2.
The worst that could happen in this respect is that the car develops notable vibration at acceleration. Most likely due to the wear of the rubber unit under the front shock absorber. Because after replacing the repair kit nr.59 all vibration was gone. I assume that also the wrong tyre wear pattern is not likely to happen either.