I have one of these machines, they are EXCEPTIONALLY quiet to the point that you really won't know the machine's washing other than hearing a very slight splashing noise. They're extremely well sound proofed.
The spin does make some noise, but not very much. It's vastly more silent than any machine i've owned previously.
With any machine, wooden floors can cause issues. The problem is that the machine will be sitting on a number of different boards all of which will move independently. This can create considerable vibration regardless of the design of the machine. Our Miele would vibrate quite a lot when it was installed on this type of surface.
If you must install it on a wooden floor you would be advised to bolt a large thick block of plywood into the beams supporting the floor to provide stability.