Sadly, the Cosmos seems to offer nothing of note... inside out tracking is nice of course, but the Index will do a better job of tracking overall with base stations (they're still superior), and it's not like you aren't still tethered with the Cosmos, so for now, this is hardly much of a selling point or advantage (or cost saving). The controllers are where the Index really overtakes the Cosmos though... every example of these in action, and the feedback we're already seeing, demonstrates how much a leap forwards they are, and the potential for immersion if devs utilise their full functionality is incredible. It leaves the Cosmos standing in no man's land given its price point. Obviously we will see when both of these are in the wild and get some proper real world feedback, but at this point in time it's hard to see why anyone looking at a top end VR solution with £1K to spend would opt for the Cosmos.