Got my new pixel 2 XL RMA today. Screen is whiter, or brighter I think. At 20% brightness it's really bright. No visible burn in yet, I see more of a uniform grey when I look at a grey full screen background compared to my old phone.
Also, the screen seems to have very minimal blue shift compared to my old pixel 2 XL. It's barely visible and only at odd angles but I say it's better than the last one too by a lot.
Coincidentally my roommate also RMA'd his XL too and the one he got back, the screen is definitely not as white or bright as mine. He said his blue shift is still somewhat visible but I found it to be not a concern. It's not noticeable just like his first phone. He's still setting his up so I'll see if the screen changes once the setup is done but mine is definitely more brighter and sharper it seems.
If I have to RMA his phone again we will do it and hope he gets a better one. But I don't think there will be any need.