All suspension bikes seem to be more vocal than hardtails irrespective of bushes or bearings. Carbon frames tend to highlight this by amplifying the sound of any small thing sufficiently that everyone around me complains.
I have been trying a range of different bearings to find something Stanmerproof.
Bearings have a code that determines size and shielding etc. but quality is a little more difficult to measure. Most bearings use caged balls but some are double row which means tiny ball bearings. These need good seals to repel the mud. I examined several different types of bearings before fitting and found the grease quantity varied, the seal edge gap was different and the smoothness of the bearing when turned in your fingers even changed between manufacturers.
I fitted the metal shielded bearings first and ran them for a while. The seal was much better than I expected and there was no impact damage from jammed mud or stones on the outside. The main fault was wear even with a full grease quantity. Any water penetration killed them quite quickly though. I ran two sets to find an average and give a B.
I tried the rubber shield bearings next which are more common (but the same price). I expected the seal to be better and some physical damage but found the seals to be poorer and lifetime was reduced. Photo shows the condition with the seal removed. As the seals were poorer these get C.
I have had three different suspension bikes and all of them need servicing before you think necessary to keep them running smoothly. I strip and clean the bike frequently including removing the fork and removing links and triangles and this forces me to check the bearings. You can check yours by removing the air from the shock, perhaps the shock itself and move the rear end with the wheel removed. If it is not super smooth it needs fixing.
Some older bikes need specialist tools, some newer ones supply links with bearings fitted which is a quicker change. Changing bearings is usually a mid range technical job on a bike to allow for using a drift and a bearing press or vice. Damage is easy if your hammer is near the top of your tool box.
As nothing is Stanmerproof yet I am now running some more expensive bearings (SKF) and my bike is now quieter and even surprised a badger last week by sneaking up behind him without an alarming squeak. I will update this report as soon as it begins to squeak again but hoping to give them an A this time.