Ya, the Rift S lens are pretty hard to beat, that's for sure. The Halo headband is also very nice. Unfortunately the rest of the design has left a lot to be desired and it also had a lot of early teething problems (eg. poor audio, no ipd adjustment, screen flashing, poor tracking, and grip/fire button lag). Seems like most of these, 6 months later, are mostly fixed. I actually pre-ordered/bought a Rift S last May and after just over 3 weeks use I sent it back for a refund and went back to my good old Rift cv1 w/2x sensors.
I'm looking forward to getting my pre-ordered Cosmos early next week and I hope it will be a slight upgrade to my existing Rift cv1 w/2x sensors. Time will tell I guess. In your case, only you can decide whether or not the Cosmos is a good upgrade to your current Rift S. Good luck deciding!