I replaced the rear wheel bearings on my w124 ('86 300e). Once you get the wheel carrier out, it is a straight forward process.

Make sure that the person who replaces the bearings puts the dust sheild back in its correct orientation and also make sure that they don't get bent. Or else, they will be rubbing against other components and creating a racket down under.

If you are going to remove the rear wheel carrier, it may be a good time to replace some of the rear suspension links and if necessary the sub-frame mount too. I replaced all the rear suspension links when I had the carrier out but not the sub-frame mounts and I am regretting not replacing the sub-frame mounts.

After replacing my rear wheel bearings, the rear end of my car is very quiet.

Now, I need to get the front ends done.

Good luck and let us know how it goes.