Just posted this over on XDA, thought relevant here.
Picked up my new V30 tonight (manuf Oct).. What I can say about the display:
1. On a completely white background at 15% brightness (what I would typically use), I can barely make out a small band at the bottom. I can't notice it under any other circumstances. I'll stare at the screen a little later on, but I'm 99% sure that my particular device is fine. There is no such lines on my Galaxy S7 flat that is one year old.
2. There is a blue tint when tilting the device that is not an issue with me. When I tilt my Galaxy S7 I don't see any tinting.
That said, the display is perfectly fine, but if compared side by side with the Galaxy S7 you can see that the Samsung display is a little better, especially if viewing at an angle. To be honest, it is not something I would have noticed had I not put the two side by side.
The carrier rep said that they have not had any complaints from customers since I last spoke to her on Friday and sales are going well. The first batch had some returns due to screens, but none lately.
I say if you are worried about the display, then those worries might be behind you. Just make sure you are aware of your carrier's return policies and have a look before settling on the device.
Off topic: Only thing that has me worried so far is that the fingerprint scanner does not like my right index finger (it has a scar). The scanner kept complaining that it was dirty when I was using that finger near where the scarred part is. No other fingerprint scanner has ever had an issue with the scar.