EDIT2:
I moved my HMD and only one base station to the PC desk for game development and I loaded the Unity3d SteamVR sample scene. It shows the exact position and rotation of the HMD and controllers. The base station is 2 meters away from the HMD.
The position vibrates within 0.2 millimeters!
The rotation vibrates within 0.18 - 0.23 degrees which is noticeable on the mirror view and in VR.
EDIT: Debug setup https://www.youtube.com/edit?video_id...
HTC VIVE, base stations 4m apart on wall mounts, headset in the middle resting on a table, covered reflective surfaces with blankets, no dropped frames.