I have had a Vive for a while. I recently got a Cosmos Elite and the tracking is horrible. The Elite uses the add-on tracking plate. I keep comparing the Cosmos to my original Vive and it is definitely a Cosmos issue because the original Vive tracks perfectly. When I move my head around with the Cosmos the display keeps shaking until the view resets but soon it starts shaking and moving the VR world again. Plus I often find when the VR starts up I am way above the floor. I signed up for the beta releases of the Vive console but that doesn't help. I have decided to return the Cosmos while I am still in the return period. Very disappointing since I do like the better resolution of the Cosmos.
