Hi,
What about the possible "clattering"?? (I don't know if this is the right word to describe it), I refer to the little up and down movements due to the gears itself. If the bed is not held into the gears, with some guides as most printers do, every time a tooth is pushing the bed, it can move upwards instead of moving in the same plane. All the more if the bed is unbalanced and one of its feet is touching the base.
I know the movement could be mostly imperceptible but when I'm trying to print something with 0.05-0.1 mm layer thickness, that little movement could be very important in terms of quality.