I played for a while last night and was pleasantly surprised at how well it ran.
 
Res: 3440x1440
Video settings: Ultra
DXR quality: Low
Core: 2085
Mem: 8000
Power: Max
Voltage: Max
Card: XC Gaming 
Cooling: EK block/backplate
 
In single player, averaged mid-50's to 60fps; low was high 40's and max was 70+. In multiplayer there was a dip across the board but not by that much. Yes that's DXR on low but in a game where you're constantly moving the difference between DXR levels is hard to notice unless you stop and stare at reflections.
 
I did try 3440x1440/Ultra/DXR Ultra and that's where you get the nose-dive into the 30's.
 
I also tried 2560x1080/Ultra/DXR Ultra. The image is both better and worse because DXR quality is increased but resolution is decreased.
 
2560x1440 was doing some funky things for me so I didn't get a chance to test but I have a feeling I will settle on 2560x1440/Ultra/DXR Ultra or stay at 3440x1440/Ultra/DXR Low.
 
Only other thing I'm curious about is the difference the in-game video settings make - I didn't change those. Will going down from Ultra to High produce a tangible jump in performance given same DXR level? I have a feeling the answer is "no." Also curious about scaling with overclock. My max OC goes to 2160/8000 but whether it'll be stable running this or make a difference I'll have to see. I know it's not going to make a noticeable difference but I'm still interested in the numbers.
 
Overall I think the entire thing was slightly overblown because, as I said, while the performance is poor at higher resolutions and DXR at ultra, you can still have DXR at low or medium on decent resolutions and you're not going to be constantly aware of the difference between that and DXR ultra as you're moving through the game.
 
This is a pic of 3440x1440/Ultra/DXR Low and you can see the reflections are still very impressive